added files via upload

Tweaks/FLEX/Utility/Runtime/Objc/FLEXObjcInternal.h

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+//
+//  FLEXObjcInternal.h
+//  FLEX
+//
+//  Created by Tanner Bennett on 11/1/18.
+//
+
+#import <Foundation/Foundation.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// The macros below are copied straight from
+// objc-internal.h, objc-private.h, objc-object.h, and objc-config.h with
+// as few modifications as possible. Changes are noted in boxed comments.
+// https://opensource.apple.com/source/objc4/objc4-723/
+// https://opensource.apple.com/source/objc4/objc4-723/runtime/objc-internal.h.auto.html
+// https://opensource.apple.com/source/objc4/objc4-723/runtime/objc-object.h.auto.html
+
+/////////////////////
+// objc-internal.h //
+/////////////////////
+
+#if __LP64__
+#define OBJC_HAVE_TAGGED_POINTERS 1
+#endif
+
+#if OBJC_HAVE_TAGGED_POINTERS
+
+#if TARGET_OS_OSX && __x86_64__
+// 64-bit Mac - tag bit is LSB
+#   define OBJC_MSB_TAGGED_POINTERS 0
+#else
+// Everything else - tag bit is MSB
+#   define OBJC_MSB_TAGGED_POINTERS 1
+#endif
+
+#if OBJC_MSB_TAGGED_POINTERS
+#   define _OBJC_TAG_MASK (1UL<<63)
+#   define _OBJC_TAG_EXT_MASK (0xfUL<<60)
+#else
+#   define _OBJC_TAG_MASK 1UL
+#   define _OBJC_TAG_EXT_MASK 0xfUL
+#endif
+
+#endif // OBJC_HAVE_TAGGED_POINTERS
+
+//////////////////////////////////////
+// originally _objc_isTaggedPointer //
+//////////////////////////////////////
+NS_INLINE BOOL flex_isTaggedPointer(const void *ptr)  {
+    #if OBJC_HAVE_TAGGED_POINTERS
+        return ((uintptr_t)ptr & _OBJC_TAG_MASK) == _OBJC_TAG_MASK;
+    #else
+        return NO;
+    #endif
+}
+
+#define FLEXPointerIsTaggedPointer(obj) flex_isTaggedPointer((__bridge void *)obj)
+
+BOOL FLEXPointerIsReadable(const void * ptr);
+
+/// @brief Assumes memory is valid and readable.
+/// @discussion objc-internal.h, objc-private.h, and objc-config.h
+/// https://blog.timac.org/2016/1124-testing-if-an-arbitrary-pointer-is-a-valid-objective-c-object/
+/// https://llvm.org/svn/llvm-project/lldb/trunk/examples/summaries/cocoa/objc_runtime.py
+/// https://blog.timac.org/2016/1124-testing-if-an-arbitrary-pointer-is-a-valid-objective-c-object/
+BOOL FLEXPointerIsValidObjcObject(const void * ptr);
+
+#ifdef __cplusplus
+}
+#endif

Tweaks/FLEX/Utility/Runtime/Objc/FLEXObjcInternal.mm

@@ -0,0 +1,196 @@
+//
+//  FLEXObjcInternal.mm
+//  FLEX
+//
+//  Created by Tanner Bennett on 11/1/18.
+//
+
+/*
+ * Copyright (c) 2005-2007 Apple Inc.  All Rights Reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#import "FLEXObjcInternal.h"
+#import <objc/runtime.h>
+// For malloc_size
+#import <malloc/malloc.h>
+// For vm_region_64
+#include <mach/mach.h>
+
+#if __arm64e__
+#include <ptrauth.h>
+#endif
+
+#define ALWAYS_INLINE inline __attribute__((always_inline))
+#define NEVER_INLINE inline __attribute__((noinline))
+
+// The macros below are copied straight from
+// objc-internal.h, objc-private.h, objc-object.h, and objc-config.h with
+// as few modifications as possible. Changes are noted in boxed comments.
+// https://opensource.apple.com/source/objc4/objc4-723/
+// https://opensource.apple.com/source/objc4/objc4-723/runtime/objc-internal.h.auto.html
+// https://opensource.apple.com/source/objc4/objc4-723/runtime/objc-object.h.auto.html
+
+/////////////////////
+// objc-internal.h //
+/////////////////////
+
+#if OBJC_HAVE_TAGGED_POINTERS
+
+///////////////////
+// objc-object.h //
+///////////////////
+
+////////////////////////////////////////////////
+// originally objc_object::isExtTaggedPointer //
+////////////////////////////////////////////////
+NS_INLINE BOOL flex_isExtTaggedPointer(const void *ptr)  {
+    return ((uintptr_t)ptr & _OBJC_TAG_EXT_MASK) == _OBJC_TAG_EXT_MASK;
+}
+
+#endif // OBJC_HAVE_TAGGED_POINTERS
+
+/////////////////////////////////////
+// FLEXObjectInternal              //
+// No Apple code beyond this point //
+/////////////////////////////////////
+
+extern "C" {
+
+BOOL FLEXPointerIsReadable(const void *inPtr) {
+    kern_return_t error = KERN_SUCCESS;
+
+    vm_size_t vmsize;
+#if __arm64e__
+    // On arm64e, we need to strip the PAC from the pointer so the adress is readable
+    vm_address_t address = (vm_address_t)ptrauth_strip(inPtr, ptrauth_key_function_pointer);
+#else
+    vm_address_t address = (vm_address_t)inPtr;
+#endif
+    vm_region_basic_info_data_t info;
+    mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT_64;
+    memory_object_name_t object;
+
+    error = vm_region_64(
+        mach_task_self(),
+        &address,
+        &vmsize,
+        VM_REGION_BASIC_INFO,
+        (vm_region_info_t)&info,
+        &info_count,
+        &object
+    );
+
+    if (error != KERN_SUCCESS) {
+        // vm_region/vm_region_64 returned an error
+        return NO;
+    } else if (!(BOOL)(info.protection & VM_PROT_READ)) {
+        return NO;
+    }
+
+#if __arm64e__
+    address = (vm_address_t)ptrauth_strip(inPtr, ptrauth_key_function_pointer);
+#else
+    address = (vm_address_t)inPtr;
+#endif
+    
+    // Read the memory
+    vm_size_t size = 0;
+    char buf[sizeof(uintptr_t)];
+    error = vm_read_overwrite(mach_task_self(), address, sizeof(uintptr_t), (vm_address_t)buf, &size);
+    if (error != KERN_SUCCESS) {
+        // vm_read_overwrite returned an error
+        return NO;
+    }
+
+    return YES;
+}
+
+/// Accepts addresses that may or may not be readable.
+/// https://blog.timac.org/2016/1124-testing-if-an-arbitrary-pointer-is-a-valid-objective-c-object/
+BOOL FLEXPointerIsValidObjcObject(const void *ptr) {
+    uintptr_t pointer = (uintptr_t)ptr;
+
+    if (!ptr) {
+        return NO;
+    }
+
+#if OBJC_HAVE_TAGGED_POINTERS
+    // Tagged pointers have 0x1 set, no other valid pointers do
+    // objc-internal.h -> _objc_isTaggedPointer()
+    if (flex_isTaggedPointer(ptr) || flex_isExtTaggedPointer(ptr)) {
+        return YES;
+    }
+#endif
+
+    // Check pointer alignment
+    if ((pointer % sizeof(uintptr_t)) != 0) {
+        return NO;
+    }
+
+    // From LLDB:
+    // Pointers in a class_t will only have bits 0 through 46 set,
+    // so if any pointer has bits 47 through 63 high, we know that this is not a valid isa
+    // https://llvm.org/svn/llvm-project/lldb/trunk/examples/summaries/cocoa/objc_runtime.py
+    if ((pointer & 0xFFFF800000000000) != 0) {
+        return NO;
+    }
+
+    // Make sure dereferencing this address won't crash
+    if (!FLEXPointerIsReadable(ptr)) {
+        return NO;
+    }
+
+    // http://www.sealiesoftware.com/blog/archive/2013/09/24/objc_explain_Non-pointer_isa.html
+    // We check if the returned class is readable because object_getClass
+    // can return a garbage value when given a non-nil pointer to a non-object
+    Class cls = object_getClass((__bridge id)ptr);
+    if (!cls || !FLEXPointerIsReadable((__bridge void *)cls)) {
+        return NO;
+    }
+    
+    // Just because this pointer is readable doesn't mean whatever is at
+    // it's ISA offset is readable. We need to do the same checks on it's ISA.
+    // Even this isn't perfect, because once we call object_isClass, we're
+    // going to dereference a member of the metaclass, which may or may not
+    // be readable itself. For the time being there is no way to access it
+    // to check here, and I have yet to hard-code a solution.
+    Class metaclass = object_getClass(cls);
+    if (!metaclass || !FLEXPointerIsReadable((__bridge void *)metaclass)) {
+        return NO;
+    }
+    
+    // Does the class pointer we got appear as a class to the runtime?
+    if (!object_isClass(cls)) {
+        return NO;
+    }
+    
+    // Is the allocation size at least as large as the expected instance size?
+    ssize_t instanceSize = class_getInstanceSize(cls);
+    if (malloc_size(ptr) < instanceSize) {
+        return NO;
+    }
+
+    return YES;
+}
+
+
+} // End extern "C"

Tweaks/FLEX/Utility/Runtime/Objc/FLEXRuntimeConstants.h

@@ -0,0 +1,79 @@
+//
+//  FLEXRuntimeConstants.h
+//  FLEX
+//
+//  Created by Tanner on 3/11/20.
+//  Copyright © 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import <objc/runtime.h>
+
+#define FLEXEncodeClass(class) ("@\"" #class "\"")
+#define FLEXEncodeObject(obj) (obj ? [NSString stringWithFormat:@"@\"%@\"", [obj class]].UTF8String : @encode(id))
+
+// Arguments 0 and 1 are self and _cmd always
+extern const unsigned int kFLEXNumberOfImplicitArgs;
+
+// See https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html#//apple_ref/doc/uid/TP40008048-CH101-SW6
+extern NSString *const kFLEXPropertyAttributeKeyTypeEncoding;
+extern NSString *const kFLEXPropertyAttributeKeyBackingIvarName;
+extern NSString *const kFLEXPropertyAttributeKeyReadOnly;
+extern NSString *const kFLEXPropertyAttributeKeyCopy;
+extern NSString *const kFLEXPropertyAttributeKeyRetain;
+extern NSString *const kFLEXPropertyAttributeKeyNonAtomic;
+extern NSString *const kFLEXPropertyAttributeKeyCustomGetter;
+extern NSString *const kFLEXPropertyAttributeKeyCustomSetter;
+extern NSString *const kFLEXPropertyAttributeKeyDynamic;
+extern NSString *const kFLEXPropertyAttributeKeyWeak;
+extern NSString *const kFLEXPropertyAttributeKeyGarbageCollectable;
+extern NSString *const kFLEXPropertyAttributeKeyOldStyleTypeEncoding;
+
+typedef NS_ENUM(NSUInteger, FLEXPropertyAttribute) {
+    FLEXPropertyAttributeTypeEncoding       = 'T',
+    FLEXPropertyAttributeBackingIvarName    = 'V',
+    FLEXPropertyAttributeCopy               = 'C',
+    FLEXPropertyAttributeCustomGetter       = 'G',
+    FLEXPropertyAttributeCustomSetter       = 'S',
+    FLEXPropertyAttributeDynamic            = 'D',
+    FLEXPropertyAttributeGarbageCollectible = 'P',
+    FLEXPropertyAttributeNonAtomic          = 'N',
+    FLEXPropertyAttributeOldTypeEncoding    = 't',
+    FLEXPropertyAttributeReadOnly           = 'R',
+    FLEXPropertyAttributeRetain             = '&',
+    FLEXPropertyAttributeWeak               = 'W'
+}; //NS_SWIFT_NAME(FLEX.PropertyAttribute);
+
+typedef NS_ENUM(char, FLEXTypeEncoding) {
+    FLEXTypeEncodingNull             = '\0',
+    FLEXTypeEncodingUnknown          = '?',
+    FLEXTypeEncodingChar             = 'c',
+    FLEXTypeEncodingInt              = 'i',
+    FLEXTypeEncodingShort            = 's',
+    FLEXTypeEncodingLong             = 'l',
+    FLEXTypeEncodingLongLong         = 'q',
+    FLEXTypeEncodingUnsignedChar     = 'C',
+    FLEXTypeEncodingUnsignedInt      = 'I',
+    FLEXTypeEncodingUnsignedShort    = 'S',
+    FLEXTypeEncodingUnsignedLong     = 'L',
+    FLEXTypeEncodingUnsignedLongLong = 'Q',
+    FLEXTypeEncodingFloat            = 'f',
+    FLEXTypeEncodingDouble           = 'd',
+    FLEXTypeEncodingLongDouble       = 'D',
+    FLEXTypeEncodingCBool            = 'B',
+    FLEXTypeEncodingVoid             = 'v',
+    FLEXTypeEncodingCString          = '*',
+    FLEXTypeEncodingObjcObject       = '@',
+    FLEXTypeEncodingObjcClass        = '#',
+    FLEXTypeEncodingSelector         = ':',
+    FLEXTypeEncodingArrayBegin       = '[',
+    FLEXTypeEncodingArrayEnd         = ']',
+    FLEXTypeEncodingStructBegin      = '{',
+    FLEXTypeEncodingStructEnd        = '}',
+    FLEXTypeEncodingUnionBegin       = '(',
+    FLEXTypeEncodingUnionEnd         = ')',
+    FLEXTypeEncodingQuote            = '\"',
+    FLEXTypeEncodingBitField         = 'b',
+    FLEXTypeEncodingPointer          = '^',
+    FLEXTypeEncodingConst            = 'r'
+}; //NS_SWIFT_NAME(FLEX.TypeEncoding);

Tweaks/FLEX/Utility/Runtime/Objc/FLEXRuntimeConstants.m

@@ -0,0 +1,24 @@
+//
+//  FLEXRuntimeConstants.m
+//  FLEX
+//
+//  Created by Tanner on 3/11/20.
+//  Copyright © 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXRuntimeConstants.h"
+
+const unsigned int kFLEXNumberOfImplicitArgs = 2;
+
+NSString *const kFLEXPropertyAttributeKeyTypeEncoding = @"T";
+NSString *const kFLEXPropertyAttributeKeyBackingIvarName = @"V";
+NSString *const kFLEXPropertyAttributeKeyReadOnly = @"R";
+NSString *const kFLEXPropertyAttributeKeyCopy = @"C";
+NSString *const kFLEXPropertyAttributeKeyRetain = @"&";
+NSString *const kFLEXPropertyAttributeKeyNonAtomic = @"N";
+NSString *const kFLEXPropertyAttributeKeyCustomGetter = @"G";
+NSString *const kFLEXPropertyAttributeKeyCustomSetter = @"S";
+NSString *const kFLEXPropertyAttributeKeyDynamic = @"D";
+NSString *const kFLEXPropertyAttributeKeyWeak = @"W";
+NSString *const kFLEXPropertyAttributeKeyGarbageCollectable = @"P";
+NSString *const kFLEXPropertyAttributeKeyOldStyleTypeEncoding = @"t";

Tweaks/FLEX/Utility/Runtime/Objc/FLEXRuntimeSafety.h

@@ -0,0 +1,56 @@
+//
+//  FLEXRuntimeSafety.h
+//  FLEX
+//
+//  Created by Tanner on 3/25/17.
+//
+
+#import <Foundation/Foundation.h>
+#import <objc/runtime.h>
+
+#pragma mark - Classes
+
+extern NSUInteger const kFLEXKnownUnsafeClassCount;
+extern const Class * FLEXKnownUnsafeClassList(void);
+extern NSSet * FLEXKnownUnsafeClassNames(void);
+extern CFSetRef FLEXKnownUnsafeClasses;
+
+static Class cNSObject = nil, cNSProxy = nil;
+
+__attribute__((constructor))
+static void FLEXInitKnownRootClasses(void) {
+    cNSObject = [NSObject class];
+    cNSProxy = [NSProxy class];
+}
+
+static inline BOOL FLEXClassIsSafe(Class cls) {
+    // Is it nil or known to be unsafe?
+    if (!cls || CFSetContainsValue(FLEXKnownUnsafeClasses, (__bridge void *)cls)) {
+        return NO;
+    }
+    
+    // Is it a known root class?
+    if (!class_getSuperclass(cls)) {
+        return cls == cNSObject || cls == cNSProxy;
+    }
+    
+    // Probably safe
+    return YES;
+}
+
+static inline BOOL FLEXClassNameIsSafe(NSString *cls) {
+    if (!cls) return NO;
+    
+    NSSet *ignored = FLEXKnownUnsafeClassNames();
+    return ![ignored containsObject:cls];
+}
+
+#pragma mark - Ivars
+
+extern CFSetRef FLEXKnownUnsafeIvars;
+
+static inline BOOL FLEXIvarIsSafe(Ivar ivar) {
+    if (!ivar) return NO;
+
+    return !CFSetContainsValue(FLEXKnownUnsafeIvars, ivar);
+}

Tweaks/FLEX/Utility/Runtime/Objc/FLEXRuntimeSafety.m

@@ -0,0 +1,107 @@
+//
+//  FLEXRuntimeSafety.m
+//  FLEX
+//
+//  Created by Tanner on 3/25/17.
+//
+
+#import "FLEXRuntimeSafety.h"
+
+NSUInteger const kFLEXKnownUnsafeClassCount = 19;
+Class * _UnsafeClasses = NULL;
+CFSetRef FLEXKnownUnsafeClasses = nil;
+CFSetRef FLEXKnownUnsafeIvars = nil;
+
+#define FLEXClassPointerOrCFNull(name) \
+    (NSClassFromString(name) ?: (__bridge id)kCFNull)
+
+#define FLEXIvarOrCFNull(cls, name) \
+    (class_getInstanceVariable([cls class], name) ?: (void *)kCFNull)
+
+__attribute__((constructor))
+static void FLEXRuntimeSafteyInit() {
+    FLEXKnownUnsafeClasses = CFSetCreate(
+        kCFAllocatorDefault,
+        (const void **)(uintptr_t)FLEXKnownUnsafeClassList(),
+        kFLEXKnownUnsafeClassCount,
+        nil
+    );
+
+    Ivar unsafeIvars[] = {
+        FLEXIvarOrCFNull(NSURL, "_urlString"),
+        FLEXIvarOrCFNull(NSURL, "_baseURL"),
+    };
+    FLEXKnownUnsafeIvars = CFSetCreate(
+        kCFAllocatorDefault,
+        (const void **)unsafeIvars,
+        sizeof(unsafeIvars),
+        nil
+    );
+}
+
+const Class * FLEXKnownUnsafeClassList() {
+    if (!_UnsafeClasses) {
+        const Class ignored[] = {
+            FLEXClassPointerOrCFNull(@"__ARCLite__"),
+            FLEXClassPointerOrCFNull(@"__NSCFCalendar"),
+            FLEXClassPointerOrCFNull(@"__NSCFTimer"),
+            FLEXClassPointerOrCFNull(@"NSCFTimer"),
+            FLEXClassPointerOrCFNull(@"__NSGenericDeallocHandler"),
+            FLEXClassPointerOrCFNull(@"NSAutoreleasePool"),
+            FLEXClassPointerOrCFNull(@"NSPlaceholderNumber"),
+            FLEXClassPointerOrCFNull(@"NSPlaceholderString"),
+            FLEXClassPointerOrCFNull(@"NSPlaceholderValue"),
+            FLEXClassPointerOrCFNull(@"Object"),
+            FLEXClassPointerOrCFNull(@"VMUArchitecture"),
+            FLEXClassPointerOrCFNull(@"JSExport"),
+            FLEXClassPointerOrCFNull(@"__NSAtom"),
+            FLEXClassPointerOrCFNull(@"_NSZombie_"),
+            FLEXClassPointerOrCFNull(@"_CNZombie_"),
+            FLEXClassPointerOrCFNull(@"__NSMessage"),
+            FLEXClassPointerOrCFNull(@"__NSMessageBuilder"),
+            FLEXClassPointerOrCFNull(@"FigIrisAutoTrimmerMotionSampleExport"),
+            // Temporary until we have our own type encoding parser;
+            // setVectors: has an invalid type encoding and crashes NSMethodSignature
+            FLEXClassPointerOrCFNull(@"_UIPointVector"),
+        };
+        
+        assert((sizeof(ignored) / sizeof(Class)) == kFLEXKnownUnsafeClassCount);
+
+        _UnsafeClasses = (Class *)malloc(sizeof(ignored));
+        memcpy(_UnsafeClasses, ignored, sizeof(ignored));
+    }
+
+    return _UnsafeClasses;
+}
+
+NSSet * FLEXKnownUnsafeClassNames() {
+    static NSSet *set = nil;
+    if (!set) {
+        NSArray *ignored = @[
+            @"__ARCLite__",
+            @"__NSCFCalendar",
+            @"__NSCFTimer",
+            @"NSCFTimer",
+            @"__NSGenericDeallocHandler",
+            @"NSAutoreleasePool",
+            @"NSPlaceholderNumber",
+            @"NSPlaceholderString",
+            @"NSPlaceholderValue",
+            @"Object",
+            @"VMUArchitecture",
+            @"JSExport",
+            @"__NSAtom",
+            @"_NSZombie_",
+            @"_CNZombie_",
+            @"__NSMessage",
+            @"__NSMessageBuilder",
+            @"FigIrisAutoTrimmerMotionSampleExport",
+            @"_UIPointVector",
+        ];
+
+        set = [NSSet setWithArray:ignored];
+        assert(set.count == kFLEXKnownUnsafeClassCount);
+    }
+
+    return set;
+}

Tweaks/FLEX/Utility/Runtime/Objc/FLEXTypeEncodingParser.h

@@ -0,0 +1,46 @@
+//
+//  FLEXTypeEncodingParser.h
+//  FLEX
+//
+//  Created by Tanner Bennett on 8/22/19.
+//  Copyright © 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/// @return \c YES if the type is supported, \c NO otherwise
+BOOL FLEXGetSizeAndAlignment(const char *type, NSUInteger * _Nullable sizep, NSUInteger * _Nullable alignp);
+
+@interface FLEXTypeEncodingParser : NSObject
+
+/// \c cleanedEncoding is necessary because a type encoding may contain a pointer
+/// to an unsupported type. \c NSMethodSignature will pass each type to \c NSGetSizeAndAlignment
+/// which will throw an exception on unsupported struct pointers, and this exception is caught
+/// by \c NSMethodSignature, but it still bothers anyone debugging with \c objc_exception_throw
+///
+/// @param cleanedEncoding the "safe" type encoding you can pass to \c NSMethodSignature
+/// @return whether the given type encoding can be passed to
+/// \c NSMethodSignature without it throwing an exception.
++ (BOOL)methodTypeEncodingSupported:(NSString *)typeEncoding cleaned:(NSString *_Nonnull*_Nullable)cleanedEncoding;
+
+/// @return The type encoding of an individual argument in a method's type encoding string.
+/// Pass 0 to get the type of the return value. 1 and 2 are `self` and `_cmd` respectively.
++ (NSString *)type:(NSString *)typeEncoding forMethodArgumentAtIndex:(NSUInteger)idx;
+
+/// @return The size in bytes of the typeof an individual argument in a method's type encoding string.
+/// Pass 0 to get the size of the return value. 1 and 2 are `self` and `_cmd` respectively.
++ (ssize_t)size:(NSString *)typeEncoding forMethodArgumentAtIndex:(NSUInteger)idx;
+
+/// @param unaligned whether to compute the aligned or unaligned size.
+/// @return The size in bytes, or \c -1 if the type encoding is unsupported.
+/// Do not pass in the result of \c method_getTypeEncoding
++ (ssize_t)sizeForTypeEncoding:(NSString *)type alignment:(nullable ssize_t *)alignOut unaligned:(BOOL)unaligned;
+
+/// Defaults to \C unaligned:NO
++ (ssize_t)sizeForTypeEncoding:(NSString *)type alignment:(nullable ssize_t *)alignOut;
+
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/FLEXTypeEncodingParser.m

@@ -0,0 +1,900 @@
+//
+//  FLEXTypeEncodingParser.m
+//  FLEX
+//
+//  Created by Tanner Bennett on 8/22/19.
+//  Copyright © 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXTypeEncodingParser.h"
+#import "FLEXRuntimeUtility.h"
+
+#define S(__ch) ({ \
+    unichar __c = __ch; \
+    [[NSString alloc] initWithCharacters:&__c length:1]; \
+})
+
+typedef struct FLEXTypeInfo {
+    /// The size is unaligned. -1 if not supported at all.
+    ssize_t size;
+    ssize_t align;
+    /// NO if the type cannot be supported at all
+    /// YES if the type is either fully or partially supported.
+    BOOL supported;
+    /// YES if the type was only partially supported, such as in
+    /// the case of unions in pointer types, or named structure
+    /// types without member info. These can be corrected manually
+    /// since they can be fixed or replaced with less info.
+    BOOL fixesApplied;
+    /// Whether this type is a union or one of its members
+    /// recursively contains a union, exlcuding pointers.
+    ///
+    /// Unions are tricky because they're supported by
+    /// \c NSGetSizeAndAlignment but not by \c NSMethodSignature
+    /// so we need to track whenever a type contains a union
+    /// so that we can clean it out of pointer types.
+    BOOL containsUnion;
+    /// size can only be 0 if not void
+    BOOL isVoid;
+} FLEXTypeInfo;
+
+/// Type info for a completely unsupported type.
+static FLEXTypeInfo FLEXTypeInfoUnsupported = (FLEXTypeInfo){ -1, 0, NO, NO, NO, NO };
+/// Type info for the void return type.
+static FLEXTypeInfo FLEXTypeInfoVoid = (FLEXTypeInfo){ 0, 0, YES, NO, NO, YES };
+
+/// Builds type info for a fully or partially supported type.
+static inline FLEXTypeInfo FLEXTypeInfoMake(ssize_t size, ssize_t align, BOOL fixed) {
+    return (FLEXTypeInfo){ size, align, YES, fixed, NO, NO };
+}
+
+/// Builds type info for a fully or partially supported type.
+static inline FLEXTypeInfo FLEXTypeInfoMakeU(ssize_t size, ssize_t align, BOOL fixed, BOOL hasUnion) {
+    return (FLEXTypeInfo){ size, align, YES, fixed, hasUnion, NO };
+}
+
+BOOL FLEXGetSizeAndAlignment(const char *type, NSUInteger *sizep, NSUInteger *alignp) {
+    NSInteger size = 0;
+    ssize_t align = 0;
+    size = [FLEXTypeEncodingParser sizeForTypeEncoding:@(type) alignment:&align];
+    
+    if (size == -1) {
+        return NO;
+    }
+    
+    if (sizep) {
+        *sizep = (NSUInteger)size;
+    }
+    
+    if (alignp) {
+        *alignp = (NSUInteger)size;
+    }
+    
+    return YES;
+}
+
+@interface FLEXTypeEncodingParser ()
+@property (nonatomic, readonly) NSScanner *scan;
+@property (nonatomic, readonly) NSString *scanned;
+@property (nonatomic, readonly) NSString *unscanned;
+@property (nonatomic, readonly) char nextChar;
+
+/// Replacements are made to this string as we scan as needed
+@property (nonatomic) NSMutableString *cleaned;
+/// Offset for \e further replacements to be made within \c cleaned
+@property (nonatomic, readonly) NSUInteger cleanedReplacingOffset;
+@end
+
+@implementation FLEXTypeEncodingParser
+
+- (NSString *)scanned {
+    return [self.scan.string substringToIndex:self.scan.scanLocation];
+}
+
+- (NSString *)unscanned {
+    return [self.scan.string substringFromIndex:self.scan.scanLocation];
+}
+
+#pragma mark Initialization
+
+- (id)initWithObjCTypes:(NSString *)typeEncoding {
+    self = [super init];
+    if (self) {
+        _scan = [NSScanner scannerWithString:typeEncoding];
+        _scan.caseSensitive = YES;
+        _cleaned = typeEncoding.mutableCopy;
+    }
+
+    return self;
+}
+
+
+#pragma mark Public
+
++ (BOOL)methodTypeEncodingSupported:(NSString *)typeEncoding cleaned:(NSString * __autoreleasing *)cleanedEncoding {
+    if (!typeEncoding.length) {
+        return NO;
+    }
+    
+    FLEXTypeEncodingParser *parser = [[self alloc] initWithObjCTypes:typeEncoding];
+    
+    while (!parser.scan.isAtEnd) {
+        FLEXTypeInfo info = [parser parseNextType];
+        
+        if (!info.supported || info.containsUnion || (info.size == 0 && !info.isVoid)) {
+            return NO;
+        }
+    }
+    
+    if (cleanedEncoding) {
+        *cleanedEncoding = parser.cleaned.copy;
+    }
+    
+    return YES;
+}
+
++ (NSString *)type:(NSString *)typeEncoding forMethodArgumentAtIndex:(NSUInteger)idx {
+    FLEXTypeEncodingParser *parser = [[self alloc] initWithObjCTypes:typeEncoding];
+
+    // Scan up to the argument we want
+    for (NSUInteger i = 0; i < idx; i++) {
+        if (![parser scanPastArg]) {
+            [NSException raise:NSRangeException
+                format:@"Index %@ out of bounds for type encoding '%@'", 
+                @(idx), typeEncoding
+            ];
+        }
+    }
+
+    return [parser scanArg];
+}
+
++ (ssize_t)size:(NSString *)typeEncoding forMethodArgumentAtIndex:(NSUInteger)idx {
+    return [self sizeForTypeEncoding:[self type:typeEncoding forMethodArgumentAtIndex:idx] alignment:nil];
+}
+
++ (ssize_t)sizeForTypeEncoding:(NSString *)type alignment:(ssize_t *)alignOut {
+    return [self sizeForTypeEncoding:type alignment:alignOut unaligned:NO];
+}
+
++ (ssize_t)sizeForTypeEncoding:(NSString *)type alignment:(ssize_t *)alignOut unaligned:(BOOL)unaligned {
+    FLEXTypeInfo info = [self parseType:type];
+    
+    ssize_t size = info.size;
+    ssize_t align = info.align;
+    
+    if (info.supported) {
+        if (alignOut) {
+            *alignOut = align;
+        }
+
+        if (!unaligned) {
+            size += size % align;
+        }
+    }
+    
+    // size is -1 if not supported
+    return size;
+}
+
++ (FLEXTypeInfo)parseType:(NSString *)type cleaned:(NSString * __autoreleasing *)cleanedEncoding {
+    FLEXTypeEncodingParser *parser = [[self alloc] initWithObjCTypes:type];
+    FLEXTypeInfo info = [parser parseNextType];
+    if (cleanedEncoding) {
+        *cleanedEncoding = parser.cleaned;
+    }
+    
+    return info;
+}
+
++ (FLEXTypeInfo)parseType:(NSString *)type {
+    return [self parseType:type cleaned:nil];
+}
+
+#pragma mark Private
+
+- (NSCharacterSet *)identifierFirstCharCharacterSet {
+    static NSCharacterSet *identifierFirstSet = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        NSString *allowed = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$";
+        identifierFirstSet = [NSCharacterSet characterSetWithCharactersInString:allowed];
+    });
+    
+    return identifierFirstSet;
+}
+
+- (NSCharacterSet *)identifierCharacterSet {
+    static NSCharacterSet *identifierSet = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        NSString *allowed = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$1234567890";
+        identifierSet = [NSCharacterSet characterSetWithCharactersInString:allowed];
+    });
+    
+    return identifierSet;
+}
+
+- (char)nextChar {
+    NSScanner *scan = self.scan;
+    return [scan.string characterAtIndex:scan.scanLocation];
+}
+
+/// For scanning struct/class names
+- (NSString *)scanIdentifier {
+    NSString *prefix = nil, *suffix = nil;
+    
+    // Identifiers cannot start with a number
+    if (![self.scan scanCharactersFromSet:self.identifierFirstCharCharacterSet intoString:&prefix]) {
+        return nil;
+    }
+    
+    // Optional because identifier may just be one character
+    [self.scan scanCharactersFromSet:self.identifierCharacterSet intoString:&suffix];
+    
+    if (suffix) {
+        return [prefix stringByAppendingString:suffix];
+    }
+    
+    return prefix;
+}
+
+/// @return the size in bytes
+- (ssize_t)sizeForType:(FLEXTypeEncoding)type {
+    switch (type) {
+        case FLEXTypeEncodingChar: return sizeof(char);
+        case FLEXTypeEncodingInt: return sizeof(int);
+        case FLEXTypeEncodingShort: return sizeof(short);
+        case FLEXTypeEncodingLong: return sizeof(long);
+        case FLEXTypeEncodingLongLong: return sizeof(long long);
+        case FLEXTypeEncodingUnsignedChar: return sizeof(unsigned char);
+        case FLEXTypeEncodingUnsignedInt: return sizeof(unsigned int);
+        case FLEXTypeEncodingUnsignedShort: return sizeof(unsigned short);
+        case FLEXTypeEncodingUnsignedLong: return sizeof(unsigned long);
+        case FLEXTypeEncodingUnsignedLongLong: return sizeof(unsigned long long);
+        case FLEXTypeEncodingFloat: return sizeof(float);
+        case FLEXTypeEncodingDouble: return sizeof(double);
+        case FLEXTypeEncodingLongDouble: return sizeof(long double);
+        case FLEXTypeEncodingCBool: return sizeof(_Bool);
+        case FLEXTypeEncodingVoid: return 0;
+        case FLEXTypeEncodingCString: return sizeof(char *);
+        case FLEXTypeEncodingObjcObject:  return sizeof(id);
+        case FLEXTypeEncodingObjcClass:  return sizeof(Class);
+        case FLEXTypeEncodingSelector: return sizeof(SEL);
+        // Unknown / '?' is typically a pointer. In the rare case
+        // it isn't, such as in '{?=...}', it is never passed here.
+        case FLEXTypeEncodingUnknown:
+        case FLEXTypeEncodingPointer: return sizeof(uintptr_t);
+
+        default: return -1;
+    }
+}
+
+- (FLEXTypeInfo)parseNextType {
+    NSUInteger start = self.scan.scanLocation;
+
+    // Check for void first
+    if ([self scanChar:FLEXTypeEncodingVoid]) {
+        // Skip argument frame for method signatures
+        [self scanSize];
+        return FLEXTypeInfoVoid;
+    }
+
+    // Scan optional const
+    [self scanChar:FLEXTypeEncodingConst];
+
+    // Check for pointer, then scan next
+    if ([self scanChar:FLEXTypeEncodingPointer]) {
+        // Recurse to scan something else
+        NSUInteger pointerTypeStart = self.scan.scanLocation;
+        if ([self scanPastArg]) {
+            // Make sure the pointer type is supported, and clean it if not
+            NSUInteger pointerTypeLength = self.scan.scanLocation - pointerTypeStart;
+            NSString *pointerType = [self.scan.string
+                substringWithRange:NSMakeRange(pointerTypeStart, pointerTypeLength)
+            ];
+            
+            // Deeeep nested cleaning info gets lost here
+            NSString *cleaned = nil;
+            FLEXTypeInfo info = [self.class parseType:pointerType cleaned:&cleaned];
+            BOOL needsCleaning = !info.supported || info.containsUnion || info.fixesApplied;
+            
+            // Clean the type if it is unsupported, malformed, or contains a union.
+            // (Unions are supported by NSGetSizeAndAlignment but not
+            // supported by NSMethodSignature for some reason)
+            if (needsCleaning) {
+                // If unsupported, no cleaning occurred in parseType:cleaned: above.
+                // Otherwise, the type is partially supported and we did clean it,
+                // and we will replace this type with the cleaned type from above.
+                if (!info.supported || info.containsUnion) {
+                    cleaned = [self cleanPointeeTypeAtLocation:pointerTypeStart];
+                }
+                
+                NSInteger offset = self.cleanedReplacingOffset;
+                NSInteger location = pointerTypeStart - offset;
+                [self.cleaned replaceCharactersInRange:NSMakeRange(
+                    location, pointerTypeLength
+                ) withString:cleaned];
+            }
+            
+            // Skip optional frame offset
+            [self scanSize];
+            
+            ssize_t size = [self sizeForType:FLEXTypeEncodingPointer];
+            return FLEXTypeInfoMake(size, size, !info.supported || info.fixesApplied);
+        } else {
+            // Scan failed, abort
+            self.scan.scanLocation = start;
+            return FLEXTypeInfoUnsupported;
+        }
+    }
+
+    // Check for struct/union/array
+    char next = self.nextChar;
+    BOOL didScanSUA = YES, structOrUnion = NO, isUnion = NO;
+    FLEXTypeEncoding opening = FLEXTypeEncodingNull, closing = FLEXTypeEncodingNull;
+    switch (next) {
+        case FLEXTypeEncodingStructBegin:
+            structOrUnion = YES;
+            opening = FLEXTypeEncodingStructBegin;
+            closing = FLEXTypeEncodingStructEnd;
+            break;
+        case FLEXTypeEncodingUnionBegin:
+            structOrUnion = isUnion = YES;
+            opening = FLEXTypeEncodingUnionBegin;
+            closing = FLEXTypeEncodingUnionEnd;
+            break;
+        case FLEXTypeEncodingArrayBegin:
+            opening = FLEXTypeEncodingArrayBegin;
+            closing = FLEXTypeEncodingArrayEnd;
+            break;
+            
+        default:
+            didScanSUA = NO;
+            break;
+    }
+    
+    if (didScanSUA) {
+        BOOL containsUnion = isUnion;
+        BOOL fixesApplied = NO;
+        
+        NSUInteger backup = self.scan.scanLocation;
+
+        // Ensure we have a closing tag
+        if (![self scanPair:opening close:closing]) {
+            // Scan failed, abort
+            self.scan.scanLocation = start;
+            return FLEXTypeInfoUnsupported;
+        }
+
+        // Move cursor just after opening tag (struct/union/array)
+        NSInteger arrayCount = -1;
+        self.scan.scanLocation = backup + 1;
+        
+        if (!structOrUnion) {
+            arrayCount = [self scanSize];
+            if (!arrayCount || self.nextChar == FLEXTypeEncodingArrayEnd) {
+                // Malformed array type:
+                // 1. Arrays must have a count after the opening brace
+                // 2. Arrays must have an element type after the count
+                self.scan.scanLocation = start;
+                return FLEXTypeInfoUnsupported;
+            }
+        } else {
+            // If we encounter the ?= portion of something like {?=b8b4b1b1b18[8S]}
+            // then we skip over it, since it means nothing to us in this context.
+            // It is completely optional, and if it fails, we go right back where we were.
+            if (![self scanTypeName] && self.nextChar == FLEXTypeEncodingUnknown) {
+                // Exception: we are trying to parse {?} which is invalid
+                self.scan.scanLocation = start;
+                return FLEXTypeInfoUnsupported;
+            }
+        }
+
+        // Sum sizes of members together:
+        // Scan for bitfields before checking for other members
+        //
+        // Arrays will only have one "member," but
+        // this logic still works for them
+        ssize_t sizeSoFar = 0;
+        ssize_t maxAlign = 0;
+        NSMutableString *cleanedBackup = self.cleaned.mutableCopy;
+        
+        while (![self scanChar:closing]) {
+            next = self.nextChar;
+            // Check for bitfields, which we cannot support because
+            // type encodings for bitfields do not include alignment info
+            if (next == FLEXTypeEncodingBitField) {
+                self.scan.scanLocation = start;
+                return FLEXTypeInfoUnsupported;
+            }
+
+            // Structure fields could be named
+            if (next == FLEXTypeEncodingQuote) {
+                [self scanPair:FLEXTypeEncodingQuote close:FLEXTypeEncodingQuote];
+            }
+
+            FLEXTypeInfo info = [self parseNextType];
+            if (!info.supported || info.containsUnion) {
+                // The above call is the only time in this method where
+                // `cleaned` might be mutated recursively, so this is the
+                // only place where we need to keep and restore a backup
+                //
+                // For instance, if we've been iterating over the members
+                // of a struct and we've encountered a few pointers so far
+                // that we needed to clean, and suddenly we come across an
+                // unsupported member, we need to be able to "rewind" and
+                // undo any changes to `self.cleaned` so that the parent
+                // call in the call stack can wipe the current structure
+                // clean entirely if needed. Example below:
+                //
+                //      Initial: ^{foo=^{pair<d,d>}{^pair<i,i>}{invalid_type<d>}}
+                //                       v-- here
+                //    1st clean: ^{foo=^{?=}{^pair<i,i>}{invalid_type<d>}
+                //                           v-- here
+                //    2nd clean: ^{foo=^{?=}{?=}{invalid_type<d>}
+                //                               v-- here
+                //  Can't clean: ^{foo=^{?=}{?=}{invalid_type<d>}
+                //                 v-- to here
+                //       Rewind: ^{foo=^{pair<d,d>}{^pair<i,i>}{invalid_type<d>}}
+                //  Final clean: ^{foo=}
+                self.cleaned = cleanedBackup;
+                self.scan.scanLocation = start;
+                return FLEXTypeInfoUnsupported;
+            }
+            
+            // Unions are the size of their largest member,
+            // arrays are element.size x length, and
+            // structs are the sum of their members
+            if (structOrUnion) {
+                if (isUnion) { // Union
+                    sizeSoFar = MAX(sizeSoFar, info.size);
+                } else { // Struct
+                    sizeSoFar += info.size;
+                }
+            } else { // Array
+                sizeSoFar = info.size * arrayCount;
+            }
+            
+            // Propogate the max alignment and other metadata
+            maxAlign = MAX(maxAlign, info.align);
+            containsUnion = containsUnion || info.containsUnion;
+            fixesApplied = fixesApplied || info.fixesApplied;
+        }
+        
+        // Skip optional frame offset
+        [self scanSize];
+
+        return FLEXTypeInfoMakeU(sizeSoFar, maxAlign, fixesApplied, containsUnion);
+    }
+    
+    // Scan single thing and possible size and return
+    ssize_t size = -1;
+    char t = self.nextChar;
+    switch (t) {
+        case FLEXTypeEncodingUnknown:
+        case FLEXTypeEncodingChar:
+        case FLEXTypeEncodingInt:
+        case FLEXTypeEncodingShort:
+        case FLEXTypeEncodingLong:
+        case FLEXTypeEncodingLongLong:
+        case FLEXTypeEncodingUnsignedChar:
+        case FLEXTypeEncodingUnsignedInt:
+        case FLEXTypeEncodingUnsignedShort:
+        case FLEXTypeEncodingUnsignedLong:
+        case FLEXTypeEncodingUnsignedLongLong:
+        case FLEXTypeEncodingFloat:
+        case FLEXTypeEncodingDouble:
+        case FLEXTypeEncodingLongDouble:
+        case FLEXTypeEncodingCBool:
+        case FLEXTypeEncodingCString:
+        case FLEXTypeEncodingSelector:
+        case FLEXTypeEncodingBitField: {
+            self.scan.scanLocation++;
+            // Skip optional frame offset
+            [self scanSize];
+            
+            if (t == FLEXTypeEncodingBitField) {
+                self.scan.scanLocation = start;
+                return FLEXTypeInfoUnsupported;
+            } else {
+                // Compute size
+                size = [self sizeForType:t];
+            }
+        }
+            break;
+        
+        case FLEXTypeEncodingObjcObject:
+        case FLEXTypeEncodingObjcClass: {
+            self.scan.scanLocation++;
+            // These might have numbers OR quotes after them
+            // Skip optional frame offset
+            [self scanSize];
+            [self scanPair:FLEXTypeEncodingQuote close:FLEXTypeEncodingQuote];
+            size = sizeof(id);
+        }
+            break;
+            
+        default: break;
+    }
+
+    if (size > 0) {
+        // Alignment of scalar types is its size
+        return FLEXTypeInfoMake(size, size, NO);
+    }
+
+    self.scan.scanLocation = start;
+    return FLEXTypeInfoUnsupported;
+}
+
+- (BOOL)scanString:(NSString *)str {
+    return [self.scan scanString:str intoString:nil];
+}
+
+- (BOOL)canScanString:(NSString *)str {
+    NSScanner *scan = self.scan;
+    NSUInteger len = str.length;
+    unichar buff1[len], buff2[len];
+    
+    [str getCharacters:buff1];
+    [scan.string getCharacters:buff2 range:NSMakeRange(scan.scanLocation, len)];
+    if (memcmp(buff1, buff2, len) == 0) {
+        return YES;
+    }
+
+    return NO;
+}
+
+- (BOOL)canScanChar:(char)c {
+    // By avoiding any ARC calls on these two objects which we know won't be
+    // free'd out from under us, we're making HUGE performance savings in this
+    // parser, because this method is one of the most-used methods of the parser.
+    // This is probably the most performance-critical method in this class.
+    __unsafe_unretained NSScanner *scan = self.scan;
+    __unsafe_unretained NSString *string = scan.string;
+    if (scan.scanLocation >= string.length) return NO;
+    
+    return [string characterAtIndex:scan.scanLocation] == c;
+}
+
+- (BOOL)scanChar:(char)c {
+    if ([self canScanChar:c]) {
+        self.scan.scanLocation++;
+        return YES;
+    }
+    
+    return NO;
+}
+
+- (BOOL)scanChar:(char)c into:(char *)ref {
+    if ([self scanChar:c]) {
+        *ref = c;
+        return YES;
+    }
+
+    return NO;
+}
+
+- (ssize_t)scanSize {
+    NSInteger size = 0;
+    if ([self.scan scanInteger:&size]) {
+        return size;
+    }
+
+    return 0;
+}
+
+- (NSString *)scanPair:(char)c1 close:(char)c2 {
+    // Starting position and string variables
+    NSUInteger start = self.scan.scanLocation;
+    NSString *s1 = S(c1);
+
+    // Scan opening tag
+    if (![self scanChar:c1]) {
+        self.scan.scanLocation = start;
+        return nil;
+    }
+
+    // Character set for scanning up to either symbol
+    NSCharacterSet *bothChars = ({
+        unichar buff[2] = { c1, c2 };
+        NSString *bothCharsStr = [[NSString alloc] initWithCharacters:buff length:2];
+        [NSCharacterSet characterSetWithCharactersInString:bothCharsStr];
+    });
+
+    // Stack for finding pairs, starting with the opening symbol
+    NSMutableArray *stack = [NSMutableArray arrayWithObject:s1];
+
+    // Algorithm for scanning to the closing end of a pair of opening/closing symbols
+    // scanUpToCharactersFromSet:intoString: returns NO if you're already at one of the chars,
+    // so we need to check if we can actually scan one if it returns NO
+    while ([self.scan scanUpToCharactersFromSet:bothChars intoString:nil] ||
+           [self canScanChar:c1] || [self canScanChar:c2]) {
+        // Closing symbol found
+        if ([self scanChar:c2]) {
+            if (!stack.count) {
+                // Abort, no matching opening symbol
+                self.scan.scanLocation = start;
+                return nil;
+            }
+
+            // Pair found, pop opening symbol
+            [stack removeLastObject];
+            // Exit loop if we reached the closing brace we needed
+            if (!stack.count) {
+                break;
+            }
+        }
+        // Opening symbol found
+        if ([self scanChar:c1]) {
+            // Begin pair
+            [stack addObject:s1];
+        }
+    }
+
+    if (stack.count) {
+        // Abort, no matching closing symbol
+        self.scan.scanLocation = start;
+        return nil;
+    }
+
+    // Slice out the string we just scanned
+    return [self.scan.string
+        substringWithRange:NSMakeRange(start, self.scan.scanLocation - start)
+    ];
+}
+
+- (BOOL)scanPastArg {
+    NSUInteger start = self.scan.scanLocation;
+
+    // Check for void first
+    if ([self scanChar:FLEXTypeEncodingVoid]) {
+        return YES;
+    }
+
+    // Scan optional const
+    [self scanChar:FLEXTypeEncodingConst];
+
+    // Check for pointer, then scan next
+    if ([self scanChar:FLEXTypeEncodingPointer]) {
+        // Recurse to scan something else
+        if ([self scanPastArg]) {
+            return YES;
+        } else {
+            // Scan failed, abort
+            self.scan.scanLocation = start;
+            return NO;
+        }
+    }
+    
+    char next = self.nextChar;
+
+    // Check for struct/union/array, scan past it
+    FLEXTypeEncoding opening = FLEXTypeEncodingNull, closing = FLEXTypeEncodingNull;
+    BOOL checkPair = YES;
+    switch (next) {
+        case FLEXTypeEncodingStructBegin:
+            opening = FLEXTypeEncodingStructBegin;
+            closing = FLEXTypeEncodingStructEnd;
+            break;
+        case FLEXTypeEncodingUnionBegin:
+            opening = FLEXTypeEncodingUnionBegin;
+            closing = FLEXTypeEncodingUnionEnd;
+            break;
+        case FLEXTypeEncodingArrayBegin:
+            opening = FLEXTypeEncodingArrayBegin;
+            closing = FLEXTypeEncodingArrayEnd;
+            break;
+            
+        default:
+            checkPair = NO;
+            break;
+    }
+    
+    if (checkPair && [self scanPair:opening close:closing]) {
+        return YES;
+    }
+
+    // Scan single thing and possible size and return
+    switch (next) {
+        case FLEXTypeEncodingUnknown:
+        case FLEXTypeEncodingChar:
+        case FLEXTypeEncodingInt:
+        case FLEXTypeEncodingShort:
+        case FLEXTypeEncodingLong:
+        case FLEXTypeEncodingLongLong:
+        case FLEXTypeEncodingUnsignedChar:
+        case FLEXTypeEncodingUnsignedInt:
+        case FLEXTypeEncodingUnsignedShort:
+        case FLEXTypeEncodingUnsignedLong:
+        case FLEXTypeEncodingUnsignedLongLong:
+        case FLEXTypeEncodingFloat:
+        case FLEXTypeEncodingDouble:
+        case FLEXTypeEncodingLongDouble:
+        case FLEXTypeEncodingCBool:
+        case FLEXTypeEncodingCString:
+        case FLEXTypeEncodingSelector:
+        case FLEXTypeEncodingBitField: {
+            self.scan.scanLocation++;
+            // Size is optional
+            [self scanSize];
+            return YES;
+        }
+        
+        case FLEXTypeEncodingObjcObject:
+        case FLEXTypeEncodingObjcClass: {
+            self.scan.scanLocation++;
+            // These might have numbers OR quotes after them
+            [self scanSize] || [self scanPair:FLEXTypeEncodingQuote close:FLEXTypeEncodingQuote];
+            return YES;
+        }
+            
+        default: break;
+    }
+
+    self.scan.scanLocation = start;
+    return NO;
+}
+
+- (NSString *)scanArg {
+    NSUInteger start = self.scan.scanLocation;
+    if (![self scanPastArg]) {
+        return nil;
+    }
+
+    return [self.scan.string
+        substringWithRange:NSMakeRange(start, self.scan.scanLocation - start)
+    ];
+}
+
+- (BOOL)scanTypeName {
+    NSUInteger start = self.scan.scanLocation;
+
+    // The ?= portion of something like {?=b8b4b1b1b18[8S]}
+    if ([self scanChar:FLEXTypeEncodingUnknown]) {
+        if (![self scanString:@"="]) {
+            // No size information available for strings like {?=}
+            self.scan.scanLocation = start;
+            return NO;
+        }
+    } else {
+        if (![self scanIdentifier] || ![self scanString:@"="]) {
+            // 1. Not a valid identifier
+            // 2. No size information available for strings like {CGPoint}
+            self.scan.scanLocation = start;
+            return NO;
+        }
+    }
+
+    return YES;
+}
+
+- (NSString *)extractTypeNameFromScanLocation:(BOOL)allowMissingTypeInfo closing:(FLEXTypeEncoding)closeTag {
+    NSUInteger start = self.scan.scanLocation;
+
+    // The ?= portion of something like {?=b8b4b1b1b18[8S]}
+    if ([self scanChar:FLEXTypeEncodingUnknown]) {
+        return @"?";
+    } else {
+        NSString *typeName = [self scanIdentifier];
+        char next = self.nextChar;
+        
+        if (!typeName) {
+            // Did not scan an identifier
+            self.scan.scanLocation = start;
+            return nil;
+        }
+        
+        switch (next) {
+            case '=':
+                return typeName;
+                
+            default: {
+                // = is non-optional unless we allowMissingTypeInfo, in whcih
+                // case the next character needs to be a closing brace
+                if (allowMissingTypeInfo && next == closeTag) {
+                    return typeName;
+                } else {
+                    // Not a valid identifier; possibly a generic C++ type
+                    // i.e. {pair<T, U>} where `name` was found as `pair`
+                    self.scan.scanLocation = start;
+                    return nil;
+                }
+            }
+        }
+    }
+}
+
+- (NSString *)cleanPointeeTypeAtLocation:(NSUInteger)scanLocation {
+    NSUInteger start = self.scan.scanLocation;
+    self.scan.scanLocation = scanLocation;
+    
+    // The return / cleanup code for when the scanned type is already clean
+    NSString * (^typeIsClean)(void) = ^NSString * {
+        NSString *clean = [self.scan.string
+            substringWithRange:NSMakeRange(scanLocation, self.scan.scanLocation - scanLocation)
+        ];
+        // Reset scan location even on success, because this method is not supposed to change it
+        self.scan.scanLocation = start;
+        return clean;
+    };
+
+    // No void, this is not a return type
+
+    // Scan optional const
+    [self scanChar:FLEXTypeEncodingConst];
+    
+    char next = self.nextChar;
+    switch (next) {
+        case FLEXTypeEncodingPointer:
+            // Recurse to scan something else
+            [self scanChar:next];
+            return [self cleanPointeeTypeAtLocation:self.scan.scanLocation];
+            
+        case FLEXTypeEncodingArrayBegin:
+            // All arrays are supported, scan past them
+            if ([self scanPair:FLEXTypeEncodingArrayBegin close:FLEXTypeEncodingArrayEnd]) {
+                return typeIsClean();
+            }
+            break;
+            
+        case FLEXTypeEncodingUnionBegin:
+            // Unions are not supported at all in NSMethodSignature
+            // We could check for the closing token to be safe, but eh
+            self.scan.scanLocation = start;
+            return @"?";
+            
+        case FLEXTypeEncodingStructBegin: {
+            FLEXTypeInfo info = [self.class parseType:self.unscanned];
+            if (info.supported && !info.fixesApplied) {
+                [self scanPastArg];
+                return typeIsClean();
+            }
+            
+            // The structure we just tried to scan is unsupported, so just return its name
+            // if it has one. If not, just return a question mark.
+            self.scan.scanLocation++; // Skip past {
+            NSString *name = [self extractTypeNameFromScanLocation:YES closing:FLEXTypeEncodingStructEnd];
+            if (name) {
+                // Got the name, scan past the closing token
+                [self.scan scanUpToString:@"}" intoString:nil];
+                if (![self scanChar:FLEXTypeEncodingStructEnd]) {
+                    // Missing struct close token
+                    self.scan.scanLocation = start;
+                    return nil;
+                }
+            } else {
+                // Did not scan valid identifier, possibly a C++ type
+                self.scan.scanLocation = start;
+                return @"{?=}";
+            }
+            
+            // Reset scan location even on success, because this method is not supposed to change it
+            self.scan.scanLocation = start;
+            return ({ // "{name=}"
+                NSMutableString *format = @"{".mutableCopy;
+                [format appendString:name];
+                [format appendString:@"=}"];
+                format;
+            });
+        }
+        
+        default:
+            break;
+    }
+    
+    // Check for other types, which in theory are all valid but whatever
+    FLEXTypeInfo info = [self parseNextType];
+    if (info.supported && !info.fixesApplied) {
+        return typeIsClean();
+    }
+    
+    self.scan.scanLocation = start;
+    return @"?";
+}
+
+- (NSUInteger)cleanedReplacingOffset {
+    return self.scan.string.length - self.cleaned.length;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXBlockDescription.h

@@ -0,0 +1,58 @@
+//
+//  FLEXBlockDescription.h
+//  FLEX
+//
+//  Created by Oliver Letterer on 2012-09-01
+//  Forked from CTObjectiveCRuntimeAdditions (MIT License)
+//  https://github.com/ebf/CTObjectiveCRuntimeAdditions
+//
+//  Copyright (c) 2020 FLEX Team-EDV Beratung Föllmer GmbH
+//  Permission is hereby granted, free of charge, to any person obtaining a copy of this
+//  software and associated documentation files (the "Software"), to deal in the Software
+//  without restriction, including without limitation the rights to use, copy, modify, merge,
+//  publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+//  to whom the Software is furnished to do so, subject to the following conditions:
+//  The above copyright notice and this permission notice shall be included in all copies or
+//  substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+//  BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+//  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#import <Foundation/Foundation.h>
+
+typedef NS_OPTIONS(NSUInteger, FLEXBlockOptions) {
+   FLEXBlockOptionHasCopyDispose = (1 << 25),
+   FLEXBlockOptionHasCtor        = (1 << 26), // helpers have C++ code
+   FLEXBlockOptionIsGlobal       = (1 << 28),
+   FLEXBlockOptionHasStret       = (1 << 29), // IFF BLOCK_HAS_SIGNATURE
+   FLEXBlockOptionHasSignature   = (1 << 30),
+};
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark -
+@interface FLEXBlockDescription : NSObject
+
++ (instancetype)describing:(id)block;
+
+@property (nonatomic, readonly, nullable) NSMethodSignature *signature;
+@property (nonatomic, readonly, nullable) NSString *signatureString;
+@property (nonatomic, readonly, nullable) NSString *sourceDeclaration;
+@property (nonatomic, readonly) FLEXBlockOptions flags;
+@property (nonatomic, readonly) NSUInteger size;
+@property (nonatomic, readonly) NSString *summary;
+@property (nonatomic, readonly) id block;
+
+- (BOOL)isCompatibleForBlockSwizzlingWithMethodSignature:(NSMethodSignature *)methodSignature;
+
+@end
+
+#pragma mark -
+@interface NSBlock : NSObject
+- (void)invoke;
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXBlockDescription.m

@@ -0,0 +1,157 @@
+//
+//  FLEXBlockDescription.m
+//  FLEX
+//
+//  Created by Oliver Letterer on 2012-09-01
+//  Forked from CTObjectiveCRuntimeAdditions (MIT License)
+//  https://github.com/ebf/CTObjectiveCRuntimeAdditions
+//
+//  Copyright (c) 2020 FLEX Team-EDV Beratung Föllmer GmbH
+//  Permission is hereby granted, free of charge, to any person obtaining a copy of this
+//  software and associated documentation files (the "Software"), to deal in the Software
+//  without restriction, including without limitation the rights to use, copy, modify, merge,
+//  publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+//  to whom the Software is furnished to do so, subject to the following conditions:
+//  The above copyright notice and this permission notice shall be included in all copies or
+//  substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+//  BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+//  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#import "FLEXBlockDescription.h"
+#import "FLEXRuntimeUtility.h"
+
+struct block_object {
+    void *isa;
+    int flags;
+    int reserved;
+    void (*invoke)(void *, ...);
+    struct block_descriptor {
+        unsigned long int reserved;    // NULL
+        unsigned long int size;     // sizeof(struct Block_literal_1)
+        // optional helper functions
+        void (*copy_helper)(void *dst, void *src);     // IFF (1<<25)
+        void (*dispose_helper)(void *src);             // IFF (1<<25)
+        // required ABI.2010.3.16
+        const char *signature;                         // IFF (1<<30)
+    } *descriptor;
+    // imported variables
+};
+
+@implementation FLEXBlockDescription
+
++ (instancetype)describing:(id)block {
+    return [[self alloc] initWithObjcBlock:block];
+}
+
+- (id)initWithObjcBlock:(id)block {
+    self = [super init];
+    if (self) {
+        _block = block;
+        
+        struct block_object *blockRef = (__bridge struct block_object *)block;
+        _flags = blockRef->flags;
+        _size = blockRef->descriptor->size;
+        
+        if (_flags & FLEXBlockOptionHasSignature) {
+            void *signatureLocation = blockRef->descriptor;
+            signatureLocation += sizeof(unsigned long int);
+            signatureLocation += sizeof(unsigned long int);
+            
+            if (_flags & FLEXBlockOptionHasCopyDispose) {
+                signatureLocation += sizeof(void(*)(void *dst, void *src));
+                signatureLocation += sizeof(void (*)(void *src));
+            }
+            
+            const char *signature = (*(const char **)signatureLocation);
+            _signatureString = @(signature);
+            
+            @try {
+                _signature = [NSMethodSignature signatureWithObjCTypes:signature];
+            } @catch (NSException *exception) { }
+        }
+        
+        NSMutableString *summary = [NSMutableString stringWithFormat:
+            @"Type signature: %@\nSize: %@\nIs global: %@\nHas constructor: %@\nIs stret: %@",
+            self.signatureString ?: @"nil", @(self.size),
+            @((BOOL)(_flags & FLEXBlockOptionIsGlobal)),
+            @((BOOL)(_flags & FLEXBlockOptionHasCtor)),
+            @((BOOL)(_flags & FLEXBlockOptionHasStret))
+        ];
+        
+        if (!self.signature) {
+            [summary appendFormat:@"\nNumber of arguments: %@", @(self.signature.numberOfArguments)];
+        }
+        
+        _summary = summary.copy;
+        _sourceDeclaration = [self buildLikelyDeclaration];
+    }
+    
+    return self;
+}
+
+- (BOOL)isCompatibleForBlockSwizzlingWithMethodSignature:(NSMethodSignature *)methodSignature {
+    if (!self.signature) {
+        return NO;
+    }
+    
+    if (self.signature.numberOfArguments != methodSignature.numberOfArguments + 1) {
+        return NO;
+    }
+    
+    if (strcmp(self.signature.methodReturnType, methodSignature.methodReturnType) != 0) {
+        return NO;
+    }
+    
+    for (int i = 0; i < methodSignature.numberOfArguments; i++) {
+        if (i == 1) {
+            // SEL in method, IMP in block
+            if (strcmp([methodSignature getArgumentTypeAtIndex:i], ":") != 0) {
+                return NO;
+            }
+            
+            if (strcmp([self.signature getArgumentTypeAtIndex:i + 1], "^?") != 0) {
+                return NO;
+            }
+        } else {
+            if (strcmp([self.signature getArgumentTypeAtIndex:i], [self.signature getArgumentTypeAtIndex:i + 1]) != 0) {
+                return NO;
+            }
+        }
+    }
+    
+    return YES;
+}
+
+- (NSString *)buildLikelyDeclaration {
+    NSMethodSignature *signature = self.signature;
+    NSUInteger numberOfArguments = signature.numberOfArguments;
+    const char *returnType       = signature.methodReturnType;
+    
+    // Return type
+    NSMutableString *decl = [NSMutableString stringWithString:@"^"];
+    if (returnType[0] != FLEXTypeEncodingVoid) {
+        [decl appendString:[FLEXRuntimeUtility readableTypeForEncoding:@(returnType)]];
+        [decl appendString:@" "];
+    }
+    
+    // Arguments
+    if (numberOfArguments) {
+        [decl appendString:@"("];
+        for (NSUInteger i = 1; i < numberOfArguments; i++) {
+            const char *argType = [self.signature getArgumentTypeAtIndex:i] ?: "?";
+            NSString *readableArgType = [FLEXRuntimeUtility readableTypeForEncoding:@(argType)];
+            [decl appendFormat:@"%@ arg%@, ", readableArgType, @(i)];
+        }
+        
+        [decl deleteCharactersInRange:NSMakeRange(decl.length-2, 2)];
+        [decl appendString:@")"];
+    }
+    
+    return decl.copy;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXClassBuilder.h

@@ -0,0 +1,80 @@
+//
+//  FLEXClassBuilder.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/3/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+@class FLEXIvarBuilder, FLEXMethodBase, FLEXProperty, FLEXProtocol;
+
+
+#pragma mark FLEXClassBuilder
+@interface FLEXClassBuilder : NSObject
+
+@property (nonatomic, readonly) Class workingClass;
+
+/// Begins constructing a class with the given name.
+///
+/// This new class will implicitly inherits from \c NSObject with \c 0 extra bytes.
+/// Classes created this way must be registered with \c -registerClass before being used.
++ (instancetype)allocateClass:(NSString *)name;
+/// Begins constructing a class with the given name and superclass.
+/// @discussion Calls \c -allocateClass:superclass:extraBytes: with \c 0 extra bytes.
+/// Classes created this way must be registered with \c -registerClass before being used.
++ (instancetype)allocateClass:(NSString *)name superclass:(Class)superclass;
+/// Begins constructing a new class object with the given name and superclass.
+/// @discussion Pass \c nil to \e superclass to create a new root class.
+/// Classes created this way must be registered with \c -registerClass before being used.
++ (instancetype)allocateClass:(NSString *)name superclass:(Class)superclass extraBytes:(size_t)bytes;
+/// Begins constructing a new root class object with the given name and \c 0 extra bytes.
+/// @discussion Classes created this way must be registered with \c -registerClass before being used.
++ (instancetype)allocateRootClass:(NSString *)name;
+/// Use this to modify existing classes. @warning You cannot add instance variables to existing classes.
++ (instancetype)builderForClass:(Class)cls;
+
+/// @return Any methods that failed to be added.
+- (NSArray<FLEXMethodBase *> *)addMethods:(NSArray<FLEXMethodBase *> *)methods;
+/// @return Any properties that failed to be added.
+- (NSArray<FLEXProperty *> *)addProperties:(NSArray<FLEXProperty *> *)properties;
+/// @return Any protocols that failed to be added.
+- (NSArray<FLEXProtocol *> *)addProtocols:(NSArray<FLEXProtocol *> *)protocols;
+/// @warning Adding Ivars to existing classes is not supported and will always fail.
+- (NSArray<FLEXIvarBuilder *> *)addIvars:(NSArray<FLEXIvarBuilder *> *)ivars;
+
+/// Finalizes construction of a new class.
+/// @discussion Once a class is registered, instance variables cannot be added.
+/// @note Raises an exception if called on a previously registered class.
+- (Class)registerClass;
+/// Uses \c objc_lookupClass to determine if the working class is registered.
+@property (nonatomic, readonly) BOOL isRegistered;
+
+@end
+
+
+#pragma mark FLEXIvarBuilder
+@interface FLEXIvarBuilder : NSObject
+
+/// Consider using the \c FLEXIvarBuilderWithNameAndType() macro below. 
+/// @param name The name of the Ivar, such as \c \@"_value".
+/// @param size The size of the Ivar. Usually \c sizeof(type). For objects, this is \c sizeof(id).
+/// @param alignment The alignment of the Ivar. Usually \c log2(sizeof(type)).
+/// @param encoding The type encoding of the Ivar. For objects, this is \c \@(\@encode(id)), and for others it is \c \@(\@encode(type)).
++ (instancetype)name:(NSString *)name size:(size_t)size alignment:(uint8_t)alignment typeEncoding:(NSString *)encoding;
+
+@property (nonatomic, readonly) NSString *name;
+@property (nonatomic, readonly) NSString *encoding;
+@property (nonatomic, readonly) size_t   size;
+@property (nonatomic, readonly) uint8_t  alignment;
+
+@end
+
+
+#define FLEXIvarBuilderWithNameAndType(nameString, type) [FLEXIvarBuilder \
+    name:nameString \
+    size:sizeof(type) \
+    alignment:log2(sizeof(type)) \
+    typeEncoding:@(@encode(type)) \
+]

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXClassBuilder.m

@@ -0,0 +1,168 @@
+//
+//  FLEXClassBuilder.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/3/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXClassBuilder.h"
+#import "FLEXProperty.h"
+#import "FLEXMethodBase.h"
+#import "FLEXProtocol.h"
+#import <objc/runtime.h>
+
+
+#pragma mark FLEXClassBuilder
+
+@interface FLEXClassBuilder ()
+@property (nonatomic) NSString *name;
+@end
+
+@implementation FLEXClassBuilder
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
+#pragma mark Initializers
++ (instancetype)allocateClass:(NSString *)name {
+    return [self allocateClass:name superclass:NSObject.class];
+}
+
++ (instancetype)allocateClass:(NSString *)name superclass:(Class)superclass {
+    return [self allocateClass:name superclass:superclass extraBytes:0];
+}
+
++ (instancetype)allocateClass:(NSString *)name superclass:(Class)superclass extraBytes:(size_t)bytes {
+    NSParameterAssert(name);
+    return [[self alloc] initWithClass:objc_allocateClassPair(superclass, name.UTF8String, bytes)];
+}
+
++ (instancetype)allocateRootClass:(NSString *)name {
+    NSParameterAssert(name);
+    return [[self alloc] initWithClass:objc_allocateClassPair(Nil, name.UTF8String, 0)];
+}
+
++ (instancetype)builderForClass:(Class)cls {
+    return [[self alloc] initWithClass:cls];
+}
+
+- (id)initWithClass:(Class)cls {
+    NSParameterAssert(cls);
+    
+    self = [super init];
+    if (self) {
+        _workingClass = cls;
+        _name = NSStringFromClass(_workingClass);
+    }
+    
+    return self;
+}
+
+- (NSString *)description {
+    return [NSString stringWithFormat:@"<%@ name=%@, registered=%d>",
+            NSStringFromClass(self.class), self.name, self.isRegistered];
+}
+
+#pragma mark Building
+- (NSArray *)addMethods:(NSArray *)methods {
+    NSParameterAssert(methods.count);
+    
+    NSMutableArray *failed = [NSMutableArray new];
+    for (FLEXMethodBase *m in methods) {
+        if (!class_addMethod(self.workingClass, m.selector, m.implementation, m.typeEncoding.UTF8String)) {
+            [failed addObject:m];
+        }
+    }
+    
+    return failed;
+}
+
+- (NSArray *)addProperties:(NSArray *)properties {
+    NSParameterAssert(properties.count);
+    
+    NSMutableArray *failed = [NSMutableArray new];
+    for (FLEXProperty *p in properties) {
+        unsigned int pcount;
+        objc_property_attribute_t *attributes = [p copyAttributesList:&pcount];
+        if (!class_addProperty(self.workingClass, p.name.UTF8String, attributes, pcount)) {
+            [failed addObject:p];
+        }
+        free(attributes);
+    }
+    
+    return failed;
+}
+
+- (NSArray *)addProtocols:(NSArray *)protocols {
+    NSParameterAssert(protocols.count);
+    
+    NSMutableArray *failed = [NSMutableArray new];
+    for (FLEXProtocol *p in protocols) {
+        if (!class_addProtocol(self.workingClass, p.objc_protocol)) {
+            [failed addObject:p];
+        }
+    }
+    
+    return failed;
+}
+
+- (NSArray *)addIvars:(NSArray *)ivars {
+    NSParameterAssert(ivars.count);
+    
+    NSMutableArray *failed = [NSMutableArray new];
+    for (FLEXIvarBuilder *ivar in ivars) {
+        if (!class_addIvar(self.workingClass, ivar.name.UTF8String, ivar.size, ivar.alignment, ivar.encoding.UTF8String)) {
+            [failed addObject:ivar];
+        }
+    }
+    
+    return failed;
+}
+
+- (Class)registerClass {
+    if (self.isRegistered) {
+        [NSException raise:NSInternalInconsistencyException format:@"Class is already registered"];
+    }
+    
+    objc_registerClassPair(self.workingClass);
+    return self.workingClass;
+}
+
+- (BOOL)isRegistered {
+    return objc_lookUpClass(self.name.UTF8String) != nil;
+}
+
+@end
+
+
+#pragma mark FLEXIvarBuilder
+
+@implementation FLEXIvarBuilder
+
++ (instancetype)name:(NSString *)name size:(size_t)size alignment:(uint8_t)alignment typeEncoding:(NSString *)encoding {
+    return [[self alloc] initWithName:name size:size alignment:alignment typeEncoding:encoding];
+}
+
+- (id)initWithName:(NSString *)name size:(size_t)size alignment:(uint8_t)alignment typeEncoding:(NSString *)encoding {
+    NSParameterAssert(name); NSParameterAssert(encoding);
+    NSParameterAssert(size > 0); NSParameterAssert(alignment > 0);
+    
+    self = [super init];
+    if (self) {
+        _name      = name;
+        _encoding  = encoding;
+        _size      = size;
+        _alignment = alignment;
+    }
+    
+    return self;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXIvar.h

@@ -0,0 +1,51 @@
+//
+//  FLEXIvar.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXRuntimeConstants.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FLEXIvar : NSObject
+
++ (instancetype)ivar:(Ivar)ivar;
++ (instancetype)named:(NSString *)name onClass:(Class)cls;
+
+/// The underlying \c Ivar data structure.
+@property (nonatomic, readonly) Ivar             objc_ivar;
+
+/// The name of the instance variable.
+@property (nonatomic, readonly) NSString         *name;
+/// The type of the instance variable.
+@property (nonatomic, readonly) FLEXTypeEncoding type;
+/// The type encoding string of the instance variable.
+@property (nonatomic, readonly) NSString         *typeEncoding;
+/// The offset of the instance variable.
+@property (nonatomic, readonly) NSInteger        offset;
+/// The size of the instance variable. 0 if unknown.
+@property (nonatomic, readonly) NSUInteger       size;
+/// Describes the type encoding, size, offset, and objc_ivar
+@property (nonatomic, readonly) NSString        *details;
+/// The full path of the image that contains this ivar definition,
+/// or \c nil if this ivar was probably defined at runtime.
+@property (nonatomic, readonly, nullable) NSString *imagePath;
+
+/// For internal use
+@property (nonatomic) id tag;
+
+- (nullable id)getValue:(id)target;
+- (void)setValue:(nullable id)value onObject:(id)target;
+
+/// Calls into -getValue: and passes that value into
+/// -[FLEXRuntimeUtility potentiallyUnwrapBoxedPointer:type:]
+/// and returns the result
+- (nullable id)getPotentiallyUnboxedValue:(id)target;
+
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXIvar.m

@@ -0,0 +1,158 @@
+//
+//  FLEXIvar.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXIvar.h"
+#import "FLEXRuntimeUtility.h"
+#import "FLEXRuntimeSafety.h"
+#import "FLEXTypeEncodingParser.h"
+#import "NSString+FLEX.h"
+#include "FLEXObjcInternal.h"
+#include <dlfcn.h>
+
+@interface FLEXIvar () {
+    NSString *_flex_description;
+}
+@end
+
+@implementation FLEXIvar
+
+#pragma mark Initializers
+
++ (instancetype)ivar:(Ivar)ivar {
+    return [[self alloc] initWithIvar:ivar];
+}
+
++ (instancetype)named:(NSString *)name onClass:(Class)cls {
+    Ivar _Nullable ivar = class_getInstanceVariable(cls, name.UTF8String);
+    NSAssert(ivar, @"Cannot find ivar with name %@ on class %@", name, cls);
+    return [self ivar:ivar];
+}
+
+- (id)initWithIvar:(Ivar)ivar {
+    NSParameterAssert(ivar);
+
+    self = [super init];
+    if (self) {
+        _objc_ivar = ivar;
+        [self examine];
+    }
+
+    return self;
+}
+
+#pragma mark Other
+
+- (NSString *)description {
+    if (!_flex_description) {
+        NSString *readableType = [FLEXRuntimeUtility readableTypeForEncoding:self.typeEncoding];
+        _flex_description = [FLEXRuntimeUtility appendName:self.name toType:readableType];
+    }
+
+    return _flex_description;
+}
+
+- (NSString *)debugDescription {
+    return [NSString stringWithFormat:@"<%@ name=%@, encoding=%@, offset=%ld>",
+            NSStringFromClass(self.class), self.name, self.typeEncoding, (long)self.offset];
+}
+
+- (void)examine {
+    _name         = @(ivar_getName(self.objc_ivar) ?: "(nil)");
+    _offset       = ivar_getOffset(self.objc_ivar);
+    _typeEncoding = @(ivar_getTypeEncoding(self.objc_ivar) ?: "");
+
+    NSString *typeForDetails = _typeEncoding;
+    NSString *sizeForDetails = nil;
+    if (_typeEncoding.length) {
+        _type = (FLEXTypeEncoding)[_typeEncoding characterAtIndex:0];
+        FLEXGetSizeAndAlignment(_typeEncoding.UTF8String, &_size, nil);
+        sizeForDetails = [@(_size).stringValue stringByAppendingString:@" bytes"];
+    } else {
+        _type = FLEXTypeEncodingNull;
+        typeForDetails = @"no type info";
+        sizeForDetails = @"unknown size";
+    }
+
+    Dl_info exeInfo;
+    if (dladdr(_objc_ivar, &exeInfo)) {
+        _imagePath = exeInfo.dli_fname ? @(exeInfo.dli_fname) : nil;
+    }
+
+    _details = [NSString stringWithFormat:
+        @"%@, offset %@  —  %@",
+        sizeForDetails, @(_offset), typeForDetails
+    ];
+}
+
+- (id)getValue:(id)target {
+    id value = nil;
+    if (!FLEXIvarIsSafe(_objc_ivar) ||
+        _type == FLEXTypeEncodingNull ||
+        FLEXPointerIsTaggedPointer(target)) {
+        return nil;
+    }
+
+#ifdef __arm64__
+    // See http://www.sealiesoftware.com/blog/archive/2013/09/24/objc_explain_Non-pointer_isa.html
+    if (self.type == FLEXTypeEncodingObjcClass && [self.name isEqualToString:@"isa"]) {
+        value = object_getClass(target);
+    } else
+#endif
+    if (self.type == FLEXTypeEncodingObjcObject || self.type == FLEXTypeEncodingObjcClass) {
+        value = object_getIvar(target, self.objc_ivar);
+    } else {
+        void *pointer = (__bridge void *)target + self.offset;
+        value = [FLEXRuntimeUtility
+            valueForPrimitivePointer:pointer
+            objCType:self.typeEncoding.UTF8String
+        ];
+    }
+
+    return value;
+}
+
+- (void)setValue:(id)value onObject:(id)target {
+    const char *typeEncodingCString = self.typeEncoding.UTF8String;
+    if (self.type == FLEXTypeEncodingObjcObject) {
+        object_setIvar(target, self.objc_ivar, value);
+    } else if ([value isKindOfClass:[NSValue class]]) {
+        // Primitive - unbox the NSValue.
+        NSValue *valueValue = (NSValue *)value;
+
+        // Make sure that the box contained the correct type.
+        NSAssert(
+            strcmp(valueValue.objCType, typeEncodingCString) == 0,
+            @"Type encoding mismatch (value: %s; ivar: %s) in setting ivar named: %@ on object: %@",
+            valueValue.objCType, typeEncodingCString, self.name, target
+        );
+
+        NSUInteger bufferSize = 0;
+        if (FLEXGetSizeAndAlignment(typeEncodingCString, &bufferSize, NULL)) {
+            void *buffer = calloc(bufferSize, 1);
+            [valueValue getValue:buffer];
+            void *pointer = (__bridge void *)target + self.offset;
+            memcpy(pointer, buffer, bufferSize);
+            free(buffer);
+        }
+    }
+}
+
+- (id)getPotentiallyUnboxedValue:(id)target {
+    NSString *type = self.typeEncoding;
+    if (type.flex_typeIsNonObjcPointer && type.flex_pointeeType != FLEXTypeEncodingVoid) {
+        return [self getValue:target];
+    }
+
+    return [FLEXRuntimeUtility
+        potentiallyUnwrapBoxedPointer:[self getValue:target]
+        type:type.UTF8String
+    ];
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMethod.h

@@ -0,0 +1,96 @@
+//
+//  FLEXMethod.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXRuntimeConstants.h"
+#import "FLEXMethodBase.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/// A class representing a concrete method which already exists in a class.
+/// This class contains helper methods for swizzling or invoking the method.
+///
+/// Any of the initializers will return nil if the type encoding
+/// of the method is unsupported by `NSMethodSignature`. In general,
+/// any method whose return type or parameters involve a struct with
+/// bitfields or arrays is unsupported.
+///
+/// I do not remember why I didn't include \c signature in the base class
+/// when I originally wrote this, but I probably had a good reason. We can
+/// always go back and move it to \c FLEXMethodBase if we find we need to.
+@interface FLEXMethod : FLEXMethodBase
+
+/// Defaults to instance method
++ (nullable instancetype)method:(Method)method;
++ (nullable instancetype)method:(Method)method isInstanceMethod:(BOOL)isInstanceMethod;
+
+/// Constructs an \c FLEXMethod for the given method on the given class.
+/// @param cls the class, or metaclass if this is a class method
+/// @return The newly constructed \c FLEXMethod object, or \c nil if the
+/// specified class or its superclasses do not contain a method with the specified selector.
++ (nullable instancetype)selector:(SEL)selector class:(Class)cls;
+/// Constructs an \c FLEXMethod for the given method on the given class,
+/// only if the given class itself defines or overrides the desired method.
+/// @param cls the class, or metaclass if this is a class method
+/// @return The newly constructed \c FLEXMethod object, or \c nil \e if the
+/// specified class does not define or override, or if the specified class
+/// or its superclasses do not contain, a method with the specified selector.
++ (nullable instancetype)selector:(SEL)selector implementedInClass:(Class)cls;
+
+@property (nonatomic, readonly) Method            objc_method;
+/// The implementation of the method.
+/// @discussion Setting \c implementation will change the implementation of this method
+/// for the entire class which implements said method. It will also not modify the selector of said method.
+@property (nonatomic          ) IMP               implementation;
+/// Whether the method is an instance method or not.
+@property (nonatomic, readonly) BOOL              isInstanceMethod;
+/// The number of arguments to the method.
+@property (nonatomic, readonly) NSUInteger        numberOfArguments;
+/// The \c NSMethodSignature object corresponding to the method's type encoding.
+@property (nonatomic, readonly) NSMethodSignature *signature;
+/// Same as \e typeEncoding but with parameter sizes up front and offsets after the types.
+@property (nonatomic, readonly) NSString          *signatureString;
+/// The return type of the method.
+@property (nonatomic, readonly) FLEXTypeEncoding  *returnType;
+/// The return size of the method.
+@property (nonatomic, readonly) NSUInteger        returnSize;
+/// The full path of the image that contains this method definition,
+/// or \c nil if this ivar was probably defined at runtime.
+@property (nonatomic, readonly) NSString          *imagePath;
+
+/// Like @code - (void)foo:(int)bar @endcode
+@property (nonatomic, readonly) NSString *description;
+/// Like @code -[Class foo:] @endcode
+- (NSString *)debugNameGivenClassName:(NSString *)name;
+
+/// Swizzles the recieving method with the given method.
+- (void)swapImplementations:(FLEXMethod *)method;
+
+#define FLEXMagicNumber 0xdeadbeef
+#define FLEXArg(expr) FLEXMagicNumber,/// @encode(__typeof__(expr)), (__typeof__(expr) []){ expr }
+
+/// Sends a message to \e target, and returns it's value, or \c nil if not applicable.
+/// @discussion You may send any message with this method. Primitive return values will be wrapped
+/// in instances of \c NSNumber and \c NSValue. \c void and bitfield returning methods return \c nil.
+/// \c SEL return types are converted to strings using \c NSStringFromSelector.
+/// @return The object returned by this method, or an instance of \c NSValue or \c NSNumber containing
+/// the primitive return type, or a string for \c SEL return types.
+- (id)sendMessage:(id)target, ...;
+/// Used internally by \c sendMessage:target,. Pass \c NULL to the first parameter for void methods.
+- (void)getReturnValue:(void *)retPtr forMessageSend:(id)target, ...;
+
+@end
+
+
+@interface FLEXMethod (Comparison)
+
+- (NSComparisonResult)compare:(FLEXMethod *)method;
+
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMethod.m

@@ -0,0 +1,430 @@
+//
+//  FLEXMethod.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXMethod.h"
+#import "FLEXMirror.h"
+#import "FLEXTypeEncodingParser.h"
+#import "FLEXRuntimeUtility.h"
+#include <dlfcn.h>
+
+@implementation FLEXMethod
+@synthesize imagePath = _imagePath;
+@dynamic implementation;
+
++ (instancetype)buildMethodNamed:(NSString *)name withTypes:(NSString *)typeEncoding implementation:(IMP)implementation {
+    [NSException raise:NSInternalInconsistencyException format:@"Class instance should not be created with +buildMethodNamed:withTypes:implementation"]; return nil;
+}
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
+#pragma mark Initializers
+
++ (instancetype)method:(Method)method {
+    return [[self alloc] initWithMethod:method isInstanceMethod:YES];
+}
+
++ (instancetype)method:(Method)method isInstanceMethod:(BOOL)isInstanceMethod {
+    return [[self alloc] initWithMethod:method isInstanceMethod:isInstanceMethod];
+}
+
++ (instancetype)selector:(SEL)selector class:(Class)cls {
+    BOOL instance = !class_isMetaClass(cls);
+    // class_getInstanceMethod will return an instance method if not given
+    // not given a metaclass, or a class method if given a metaclass, but
+    // this isn't documented so we just want to be safe here.
+    Method m = instance ? class_getInstanceMethod(cls, selector) : class_getClassMethod(cls, selector);
+    if (m == NULL) return nil;
+    
+    return [self method:m isInstanceMethod:instance];
+}
+
++ (instancetype)selector:(SEL)selector implementedInClass:(Class)cls {
+    if (![cls superclass]) { return [self selector:selector class:cls]; }
+    
+    BOOL unique = [cls methodForSelector:selector] != [[cls superclass] methodForSelector:selector];
+    
+    if (unique) {
+        return [self selector:selector class:cls];
+    }
+    
+    return nil;
+}
+
+- (id)initWithMethod:(Method)method isInstanceMethod:(BOOL)isInstanceMethod {
+    NSParameterAssert(method);
+    
+    self = [super init];
+    if (self) {
+        _objc_method = method;
+        _isInstanceMethod = isInstanceMethod;
+        _signatureString = @(method_getTypeEncoding(method) ?: "?@:");
+        
+        NSString *cleanSig = nil;
+        if ([FLEXTypeEncodingParser methodTypeEncodingSupported:_signatureString cleaned:&cleanSig]) {
+            _signature = [NSMethodSignature signatureWithObjCTypes:cleanSig.UTF8String];
+        }
+
+        [self examine];
+    }
+    
+    return self;
+}
+
+
+#pragma mark Other
+
+- (NSString *)description {
+    if (!_flex_description) {
+        _flex_description = [self prettyName];
+    }
+    
+    return _flex_description;
+}
+
+- (NSString *)debugNameGivenClassName:(NSString *)name {
+    NSMutableString *string = [NSMutableString stringWithString:_isInstanceMethod ? @"-[" : @"+["];
+    [string appendString:name];
+    [string appendString:@" "];
+    [string appendString:self.selectorString];
+    [string appendString:@"]"];
+    return string;
+}
+
+- (NSString *)prettyName {
+    NSString *methodTypeString = self.isInstanceMethod ? @"-" : @"+";
+    NSString *readableReturnType = [FLEXRuntimeUtility readableTypeForEncoding:@(self.signature.methodReturnType ?: "")];
+    
+    NSString *prettyName = [NSString stringWithFormat:@"%@ (%@)", methodTypeString, readableReturnType];
+    NSArray *components = [self prettyArgumentComponents];
+
+    if (components.count) {
+        return [prettyName stringByAppendingString:[components componentsJoinedByString:@" "]];
+    } else {
+        return [prettyName stringByAppendingString:self.selectorString];
+    }
+}
+
+- (NSArray *)prettyArgumentComponents {
+    // NSMethodSignature can't handle some type encodings
+    // like ^AI@:ir* which happen to very much exist
+    if (self.signature.numberOfArguments < self.numberOfArguments) {
+        return nil;
+    }
+    
+    NSMutableArray *components = [NSMutableArray new];
+
+    NSArray *selectorComponents = [self.selectorString componentsSeparatedByString:@":"];
+    NSUInteger numberOfArguments = self.numberOfArguments;
+    
+    for (NSUInteger argIndex = 2; argIndex < numberOfArguments; argIndex++) {
+        assert(argIndex < self.signature.numberOfArguments);
+        
+        const char *argType = [self.signature getArgumentTypeAtIndex:argIndex] ?: "?";
+        NSString *readableArgType = [FLEXRuntimeUtility readableTypeForEncoding:@(argType)];
+        NSString *prettyComponent = [NSString
+            stringWithFormat:@"%@:(%@) ",
+            selectorComponents[argIndex - 2],
+            readableArgType
+        ];
+
+        [components addObject:prettyComponent];
+    }
+    
+    return components;
+}
+
+- (NSString *)debugDescription {
+    return [NSString stringWithFormat:@"<%@ selector=%@, signature=%@>",
+            NSStringFromClass(self.class), self.selectorString, self.signatureString];
+}
+
+- (void)examine {
+    _implementation    = method_getImplementation(_objc_method);
+    _selector          = method_getName(_objc_method);
+    _numberOfArguments = method_getNumberOfArguments(_objc_method);
+    _name              = NSStringFromSelector(_selector);
+    _returnType        = (FLEXTypeEncoding *)_signature.methodReturnType ?: "";
+    _returnSize        = _signature.methodReturnLength;
+}
+
+#pragma mark Public
+
+- (void)setImplementation:(IMP)implementation {
+    NSParameterAssert(implementation);
+    method_setImplementation(self.objc_method, implementation);
+    [self examine];
+}
+
+- (NSString *)typeEncoding {
+    if (!_typeEncoding) {
+        _typeEncoding = [_signatureString
+            stringByReplacingOccurrencesOfString:@"[0-9]"
+            withString:@""
+            options:NSRegularExpressionSearch
+            range:NSMakeRange(0, _signatureString.length)
+        ];
+    }
+    
+    return _typeEncoding;
+}
+
+- (NSString *)imagePath {
+    if (!_imagePath) {
+        Dl_info exeInfo;
+        if (dladdr(_implementation, &exeInfo)) {
+            _imagePath = exeInfo.dli_fname ? @(exeInfo.dli_fname) : @"";
+        }
+    }
+    
+    return _imagePath;
+}
+
+#pragma mark Misc
+
+- (void)swapImplementations:(FLEXMethod *)method {
+    method_exchangeImplementations(self.objc_method, method.objc_method);
+    [self examine];
+    [method examine];
+}
+
+// Some code borrowed from MAObjcRuntime, by Mike Ash.
+- (id)sendMessage:(id)target, ... {
+    id ret = nil;
+    va_list args;
+    va_start(args, target);
+    
+    switch (self.returnType[0]) {
+        case FLEXTypeEncodingUnknown: {
+            [self getReturnValue:NULL forMessageSend:target arguments:args];
+            break;
+        }
+        case FLEXTypeEncodingChar: {
+            char val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingInt: {
+            int val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingShort: {
+            short val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingLong: {
+            long val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingLongLong: {
+            long long val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingUnsignedChar: {
+            unsigned char val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingUnsignedInt: {
+            unsigned int val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingUnsignedShort: {
+            unsigned short val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingUnsignedLong: {
+            unsigned long val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingUnsignedLongLong: {
+            unsigned long long val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingFloat: {
+            float val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingDouble: {
+            double val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingLongDouble: {
+            long double val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = [NSValue value:&val withObjCType:self.returnType];
+            break;
+        }
+        case FLEXTypeEncodingCBool: {
+            bool val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingVoid: {
+            [self getReturnValue:NULL forMessageSend:target arguments:args];
+            return nil;
+            break;
+        }
+        case FLEXTypeEncodingCString: {
+            char *val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = @(val);
+            break;
+        }
+        case FLEXTypeEncodingObjcObject: {
+            id val = nil;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = val;
+            break;
+        }
+        case FLEXTypeEncodingObjcClass: {
+            Class val = Nil;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = val;
+            break;
+        }
+        case FLEXTypeEncodingSelector: {
+            SEL val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = NSStringFromSelector(val);
+            break;
+        }
+        case FLEXTypeEncodingArrayBegin: {
+            void *val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = [NSValue valueWithBytes:val objCType:self.signature.methodReturnType];
+            break;
+        }
+        case FLEXTypeEncodingUnionBegin:
+        case FLEXTypeEncodingStructBegin: {
+            if (self.signature.methodReturnLength) {
+                void * val = malloc(self.signature.methodReturnLength);
+                [self getReturnValue:val forMessageSend:target arguments:args];
+                ret = [NSValue valueWithBytes:val objCType:self.signature.methodReturnType];
+            } else {
+                [self getReturnValue:NULL forMessageSend:target arguments:args];
+            }
+            break;
+        }
+        case FLEXTypeEncodingBitField: {
+            [self getReturnValue:NULL forMessageSend:target arguments:args];
+            break;
+        }
+        case FLEXTypeEncodingPointer: {
+            void * val = 0;
+            [self getReturnValue:&val forMessageSend:target arguments:args];
+            ret = [NSValue valueWithPointer:val];
+            break;
+        }
+
+        default: {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"Unsupported type encoding: %s", (char *)self.returnType];
+        }
+    }
+    
+    va_end(args);
+    return ret;
+}
+
+// Code borrowed from MAObjcRuntime, by Mike Ash.
+- (void)getReturnValue:(void *)retPtr forMessageSend:(id)target, ... {
+    va_list args;
+    va_start(args, target);
+    [self getReturnValue:retPtr forMessageSend:target arguments:args];
+    va_end(args);
+}
+
+// Code borrowed from MAObjcRuntime, by Mike Ash.
+- (void)getReturnValue:(void *)retPtr forMessageSend:(id)target arguments:(va_list)args {
+    if (!_signature) {
+        return;
+    }
+    
+    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:_signature];
+    NSUInteger argumentCount = _signature.numberOfArguments;
+    
+    invocation.target = target;
+    
+    for (NSUInteger i = 2; i < argumentCount; i++) {
+        int cookie = va_arg(args, int);
+        if (cookie != FLEXMagicNumber) {
+            [NSException
+                raise:NSInternalInconsistencyException
+                format:@"%s: incorrect magic cookie %08x; make sure you didn't forget "
+                "any arguments and that all arguments are wrapped in FLEXArg().", __func__, cookie
+            ];
+        }
+        const char *typeString = va_arg(args, char *);
+        void *argPointer       = va_arg(args, void *);
+        
+        NSUInteger inSize, sigSize;
+        NSGetSizeAndAlignment(typeString, &inSize, NULL);
+        NSGetSizeAndAlignment([_signature getArgumentTypeAtIndex:i], &sigSize, NULL);
+        
+        if (inSize != sigSize) {
+            [NSException
+                raise:NSInternalInconsistencyException
+                format:@"%s:size mismatch between passed-in argument and "
+                "required argument; in type:%s (%lu) requested:%s (%lu)",
+                __func__, typeString, (long)inSize, [_signature getArgumentTypeAtIndex:i], (long)sigSize
+            ];
+        }
+        
+        [invocation setArgument:argPointer atIndex:i];
+    }
+    
+    // Hack to make NSInvocation invoke the desired implementation
+    IMP imp = [invocation methodForSelector:NSSelectorFromString(@"invokeUsingIMP:")];
+    void (*invokeWithIMP)(id, SEL, IMP) = (void *)imp;
+    invokeWithIMP(invocation, 0, _implementation);
+    
+    if (_signature.methodReturnLength && retPtr) {
+        [invocation getReturnValue:retPtr];
+    }
+}
+
+@end
+
+
+@implementation FLEXMethod (Comparison)
+
+- (NSComparisonResult)compare:(FLEXMethod *)method {
+    return [self.selectorString compare:method.selectorString];
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMethodBase.h

@@ -0,0 +1,43 @@
+//
+//  FLEXMethodBase.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/5/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+
+/// A base class for methods which encompasses those that may not
+/// have been added to a class yet. Useful on it's own for adding
+/// methods to a class, or building a new class from the ground up.
+@interface FLEXMethodBase : NSObject {
+@protected
+    SEL      _selector;
+    NSString *_name;
+    NSString *_typeEncoding;
+    IMP      _implementation;
+    
+    NSString *_flex_description;
+}
+
+/// Constructs and returns an \c FLEXSimpleMethod instance with the given name, type encoding, and implementation.
++ (instancetype)buildMethodNamed:(NSString *)name withTypes:(NSString *)typeEncoding implementation:(IMP)implementation;
+
+/// The selector of the method.
+@property (nonatomic, readonly) SEL      selector;
+/// The selector string of the method.
+@property (nonatomic, readonly) NSString *selectorString;
+/// Same as selectorString.
+@property (nonatomic, readonly) NSString *name;
+/// The type encoding of the method.
+@property (nonatomic, readonly) NSString *typeEncoding;
+/// The implementation of the method.
+@property (nonatomic, readonly) IMP      implementation;
+
+/// For internal use
+@property (nonatomic) id tag;
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMethodBase.m

@@ -0,0 +1,49 @@
+//
+//  FLEXMethodBase.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/5/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXMethodBase.h"
+
+
+@implementation FLEXMethodBase
+
+#pragma mark Initializers
+
++ (instancetype)buildMethodNamed:(NSString *)name withTypes:(NSString *)typeEncoding implementation:(IMP)implementation {
+    return [[self alloc] initWithSelector:sel_registerName(name.UTF8String) types:typeEncoding imp:implementation];
+}
+
+- (id)initWithSelector:(SEL)selector types:(NSString *)types imp:(IMP)imp {
+    NSParameterAssert(selector); NSParameterAssert(types); NSParameterAssert(imp);
+    
+    self = [super init];
+    if (self) {
+        _selector = selector;
+        _typeEncoding = types;
+        _implementation = imp;
+        _name = NSStringFromSelector(self.selector);
+    }
+    
+    return self;
+}
+
+- (NSString *)selectorString {
+    return _name;
+}
+
+#pragma mark Overrides
+
+- (NSString *)description {
+    if (!_flex_description) {
+        _flex_description = [NSString stringWithFormat:@"%@ '%@'", _name, _typeEncoding];
+    }
+
+    return _flex_description;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMirror.h

@@ -0,0 +1,97 @@
+//
+//  FLEXMirror.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/29/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import <objc/runtime.h>
+@class FLEXMethod, FLEXProperty, FLEXIvar, FLEXProtocol;
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark FLEXMirror Protocol
+NS_SWIFT_NAME(FLEXMirrorProtocol)
+@protocol FLEXMirror <NSObject>
+
+/// Swift initializer
+/// @throws If a metaclass object is passed in.
+- (instancetype)initWithSubject:(id)objectOrClass NS_SWIFT_NAME(init(reflecting:));
+
+/// The underlying object or \c Class used to create this \c FLEXMirror.
+@property (nonatomic, readonly) id   value;
+/// Whether \c value was a class or a class instance.
+@property (nonatomic, readonly) BOOL isClass;
+/// The name of the \c Class of the \c value property.
+@property (nonatomic, readonly) NSString *className;
+
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *properties;
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *classProperties;
+@property (nonatomic, readonly) NSArray<FLEXIvar *>     *ivars;
+@property (nonatomic, readonly) NSArray<FLEXMethod *>   *methods;
+@property (nonatomic, readonly) NSArray<FLEXMethod *>   *classMethods;
+@property (nonatomic, readonly) NSArray<FLEXProtocol *> *protocols;
+
+/// Super mirrors are initialized with the class that corresponds to the value passed in.
+/// If you passed in an instance of a class, it's superclass is used to create this mirror.
+/// If you passed in a class, then that class's superclass is used.
+///
+/// @note This property should be computed, not cached.
+@property (nonatomic, readonly, nullable) id<FLEXMirror> superMirror NS_SWIFT_NAME(superMirror);
+
+@end
+
+#pragma mark FLEXMirror Class
+@interface FLEXMirror : NSObject <FLEXMirror>
+
+/// Reflects an instance of an object or \c Class.
+/// @discussion \c FLEXMirror will immediately gather all useful information. Consider using the
+/// \c NSObject categories provided if your code will only use a few pieces of information,
+/// or if your code needs to run faster.
+///
+/// Regardless of whether you reflect an instance or a class object, \c methods and \c properties
+/// will be populated with instance methods and properties, and \c classMethods and \c classProperties
+/// will be populated with class methods and properties.
+///
+/// @param objectOrClass An instance of an objct or a \c Class object.
+/// @throws If a metaclass object is passed in.
+/// @return An instance of \c FLEXMirror.
++ (instancetype)reflect:(id)objectOrClass;
+
+@property (nonatomic, readonly) id   value;
+@property (nonatomic, readonly) BOOL isClass;
+@property (nonatomic, readonly) NSString *className;
+
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *properties;
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *classProperties;
+@property (nonatomic, readonly) NSArray<FLEXIvar *>     *ivars;
+@property (nonatomic, readonly) NSArray<FLEXMethod *>   *methods;
+@property (nonatomic, readonly) NSArray<FLEXMethod *>   *classMethods;
+@property (nonatomic, readonly) NSArray<FLEXProtocol *> *protocols;
+
+@property (nonatomic, readonly, nullable) FLEXMirror *superMirror NS_SWIFT_NAME(superMirror);
+
+@end
+
+
+@interface FLEXMirror (ExtendedMirror)
+
+/// @return The instance method with the given name, or \c nil if one does not exist.
+- (nullable FLEXMethod *)methodNamed:(nullable NSString *)name;
+/// @return The class method with the given name, or \c nil if one does not exist.
+- (nullable FLEXMethod *)classMethodNamed:(nullable NSString *)name;
+/// @return The instance property with the given name, or \c nil if one does not exist.
+- (nullable FLEXProperty *)propertyNamed:(nullable NSString *)name;
+/// @return The class property with the given name, or \c nil if one does not exist.
+- (nullable FLEXProperty *)classPropertyNamed:(nullable NSString *)name;
+/// @return The instance variable with the given name, or \c nil if one does not exist.
+- (nullable FLEXIvar *)ivarNamed:(nullable NSString *)name;
+/// @return The protocol with the given name, or \c nil if one does not exist.
+- (nullable FLEXProtocol *)protocolNamed:(nullable NSString *)name;
+
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXMirror.m

@@ -0,0 +1,145 @@
+//
+//  FLEXMirror.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/29/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXMirror.h"
+#import "FLEXProperty.h"
+#import "FLEXMethod.h"
+#import "FLEXIvar.h"
+#import "FLEXProtocol.h"
+#import "FLEXUtility.h"
+
+
+#pragma mark FLEXMirror
+
+@implementation FLEXMirror
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
+#pragma mark Initialization
++ (instancetype)reflect:(id)objectOrClass {
+    return [[self alloc] initWithSubject:objectOrClass];
+}
+
+- (id)initWithSubject:(id)objectOrClass {
+    NSParameterAssert(objectOrClass);
+    
+    self = [super init];
+    if (self) {
+        _value = objectOrClass;
+        [self examine];
+    }
+    
+    return self;
+}
+
+- (NSString *)description {
+    return [NSString stringWithFormat:@"<%@ %@=%@>",
+        NSStringFromClass(self.class),
+        self.isClass ? @"metaclass" : @"class",
+        self.className
+    ];
+}
+
+- (void)examine {
+    BOOL isClass = object_isClass(self.value);
+    Class cls  = isClass ? self.value : object_getClass(self.value);
+    Class meta = object_getClass(cls);
+    _className = NSStringFromClass(cls);
+    _isClass   = isClass;
+    
+    unsigned int pcount, cpcount, mcount, cmcount, ivcount, pccount;
+    Ivar *objcIvars                       = class_copyIvarList(cls, &ivcount);
+    Method *objcMethods                   = class_copyMethodList(cls, &mcount);
+    Method *objcClsMethods                = class_copyMethodList(meta, &cmcount);
+    objc_property_t *objcProperties       = class_copyPropertyList(cls, &pcount);
+    objc_property_t *objcClsProperties    = class_copyPropertyList(meta, &cpcount);
+    Protocol *__unsafe_unretained *protos = class_copyProtocolList(cls, &pccount);
+    
+    _ivars = [NSArray flex_forEachUpTo:ivcount map:^id(NSUInteger i) {
+        return [FLEXIvar ivar:objcIvars[i]];
+    }];
+    
+    _methods = [NSArray flex_forEachUpTo:mcount map:^id(NSUInteger i) {
+        return [FLEXMethod method:objcMethods[i] isInstanceMethod:YES];
+    }];
+    _classMethods = [NSArray flex_forEachUpTo:cmcount map:^id(NSUInteger i) {
+        return [FLEXMethod method:objcClsMethods[i] isInstanceMethod:NO];
+    }];
+    
+    _properties = [NSArray flex_forEachUpTo:pcount map:^id(NSUInteger i) {
+        return [FLEXProperty property:objcProperties[i] onClass:cls];
+    }];
+    _classProperties = [NSArray flex_forEachUpTo:cpcount map:^id(NSUInteger i) {
+        return [FLEXProperty property:objcClsProperties[i] onClass:meta];
+    }];
+    
+    _protocols = [NSArray flex_forEachUpTo:pccount map:^id(NSUInteger i) {
+        return [FLEXProtocol protocol:protos[i]];
+    }];
+    
+    // Cleanup
+    free(objcClsProperties);
+    free(objcProperties);
+    free(objcClsMethods);
+    free(objcMethods);
+    free(objcIvars);
+    free(protos);
+    protos = NULL;
+}
+
+#pragma mark Misc
+
+- (FLEXMirror *)superMirror {
+    Class cls = _isClass ? _value : object_getClass(_value);
+    return [FLEXMirror reflect:class_getSuperclass(cls)];
+}
+
+@end
+
+
+#pragma mark ExtendedMirror
+
+@implementation FLEXMirror (ExtendedMirror)
+
+- (id)filter:(NSArray *)array forName:(NSString *)name {
+    NSPredicate *filter = [NSPredicate predicateWithFormat:@"%K = %@", @"name", name];
+    return [array filteredArrayUsingPredicate:filter].firstObject;
+}
+
+- (FLEXMethod *)methodNamed:(NSString *)name {
+    return [self filter:self.methods forName:name];
+}
+
+- (FLEXMethod *)classMethodNamed:(NSString *)name {
+    return [self filter:self.classMethods forName:name];
+}
+
+- (FLEXProperty *)propertyNamed:(NSString *)name {
+    return [self filter:self.properties forName:name];
+}
+
+- (FLEXProperty *)classPropertyNamed:(NSString *)name {
+    return [self filter:self.classProperties forName:name];
+}
+
+- (FLEXIvar *)ivarNamed:(NSString *)name {
+    return [self filter:self.ivars forName:name];
+}
+
+- (FLEXProtocol *)protocolNamed:(NSString *)name {
+    return [self filter:self.protocols forName:name];
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProperty.h

@@ -0,0 +1,138 @@
+//
+//  FLEXProperty.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXRuntimeConstants.h"
+@class FLEXPropertyAttributes, FLEXMethodBase;
+
+
+#pragma mark FLEXProperty
+@interface FLEXProperty : NSObject
+
+/// You may use this initializer instead of \c property:onClass: if you don't need
+/// to know anything about the uniqueness of this property or where it comes from.
++ (instancetype)property:(objc_property_t)property;
+/// This initializer can be used to access additional information
+/// in an efficient manner. That information being whether this property
+/// is certainly not unique and the name of the binary image which declares it.
+/// @param cls the class, or metaclass if this is a class property.
++ (instancetype)property:(objc_property_t)property onClass:(Class)cls;
+/// @param cls the class, or metaclass if this is a class property
++ (instancetype)named:(NSString *)name onClass:(Class)cls;
+/// Constructs a new property with the given name and attributes.
++ (instancetype)propertyWithName:(NSString *)name attributes:(FLEXPropertyAttributes *)attributes;
+
+/// \c 0 if the instance was created via \c +propertyWithName:attributes,
+/// otherwise this is the first property in \c objc_properties
+@property (nonatomic, readonly) objc_property_t  objc_property;
+@property (nonatomic, readonly) objc_property_t  *objc_properties;
+@property (nonatomic, readonly) NSInteger        objc_propertyCount;
+@property (nonatomic, readonly) BOOL             isClassProperty;
+
+/// The name of the property.
+@property (nonatomic, readonly) NSString         *name;
+/// The type of the property. Get the full type from the attributes.
+@property (nonatomic, readonly) FLEXTypeEncoding type;
+/// The property's attributes.
+@property (nonatomic          ) FLEXPropertyAttributes *attributes;
+/// The (likely) setter, regardless of whether the property is readonly.
+/// For example, this might be the custom setter.
+@property (nonatomic, readonly) SEL likelySetter;
+@property (nonatomic, readonly) NSString *likelySetterString;
+/// Not valid unless initialized with the owning class.
+@property (nonatomic, readonly) BOOL likelySetterExists;
+/// The (likely) getter. For example, this might be the custom getter.
+@property (nonatomic, readonly) SEL likelyGetter;
+@property (nonatomic, readonly) NSString *likelyGetterString;
+/// Not valid unless initialized with the owning class.
+@property (nonatomic, readonly) BOOL likelyGetterExists;
+/// Always \c nil for class properties.
+@property (nonatomic, readonly) NSString *likelyIvarName;
+/// Not valid unless initialized with the owning class.
+@property (nonatomic, readonly) BOOL likelyIvarExists;
+
+/// Whether there are certainly multiple definitions of this property,
+/// such as in categories in other binary images or something.
+/// @return Whether \c objc_property matches the return value of \c class_getProperty,
+/// or \c NO if this property was not created with \c property:onClass
+@property (nonatomic, readonly) BOOL multiple;
+/// @return The bundle of the image that contains this property definition,
+/// or \c nil if this property was not created with \c property:onClass or
+/// if this property was probably defined at runtime.
+@property (nonatomic, readonly) NSString *imageName;
+/// The full path of the image that contains this property definition,
+/// or \c nil if this property was not created with \c property:onClass or
+/// if this property was probably defined at runtime.
+@property (nonatomic, readonly) NSString *imagePath;
+
+/// For internal use
+@property (nonatomic) id tag;
+
+/// @return The value of this property on \c target as given by \c -valueForKey:
+/// A source-like description of the property, with all of its attributes.
+@property (nonatomic, readonly) NSString *fullDescription;
+
+/// If this is a class property, you must class the class object.
+- (id)getValue:(id)target;
+/// Calls into -getValue: and passes that value into
+/// -[FLEXRuntimeUtility potentiallyUnwrapBoxedPointer:type:]
+/// and returns the result.
+///
+/// If this is a class property, you must class the class object.
+- (id)getPotentiallyUnboxedValue:(id)target;
+
+/// Safe to use regardless of how the \c FLEXProperty instance was initialized.
+///
+/// This uses \c self.objc_property if it exists, otherwise it uses \c self.attributes
+- (objc_property_attribute_t *)copyAttributesList:(unsigned int *)attributesCount;
+
+/// Replace the attributes of the current property in the given class,
+/// using the attributes in \c self.attributes
+///
+/// What happens when the property does not exist is undocumented.
+- (void)replacePropertyOnClass:(Class)cls;
+
+#pragma mark Convenience getters and setters
+/// @return A getter for the property with the given implementation.
+/// @discussion Consider using the \c FLEXPropertyGetter macros.
+- (FLEXMethodBase *)getterWithImplementation:(IMP)implementation;
+/// @return A setter for the property with the given implementation.
+/// @discussion Consider using the \c FLEXPropertySetter macros.
+- (FLEXMethodBase *)setterWithImplementation:(IMP)implementation;
+
+#pragma mark FLEXMethod property getter / setter macros
+// Easier than using the above methods yourself in most cases
+
+/// Takes a \c FLEXProperty and a type (ie \c NSUInteger or \c id) and
+/// uses the \c FLEXProperty's \c attribute's \c backingIvarName to get the Ivar.
+#define FLEXPropertyGetter(FLEXProperty, type) [FLEXProperty \
+    getterWithImplementation:imp_implementationWithBlock(^(id self) { \
+        return *(type *)[self getIvarAddressByName:FLEXProperty.attributes.backingIvar]; \
+    }) \
+];
+/// Takes a \c FLEXProperty and a type (ie \c NSUInteger or \c id) and
+/// uses the \c FLEXProperty's \c attribute's \c backingIvarName to set the Ivar.
+#define FLEXPropertySetter(FLEXProperty, type) [FLEXProperty \
+    setterWithImplementation:imp_implementationWithBlock(^(id self, type value) { \
+        [self setIvarByName:FLEXProperty.attributes.backingIvar value:&value size:sizeof(type)]; \
+    }) \
+];
+/// Takes a \c FLEXProperty and a type (ie \c NSUInteger or \c id) and an Ivar name string to get the Ivar.
+#define FLEXPropertyGetterWithIvar(FLEXProperty, ivarName, type) [FLEXProperty \
+    getterWithImplementation:imp_implementationWithBlock(^(id self) { \
+        return *(type *)[self getIvarAddressByName:ivarName]; \
+    }) \
+];
+/// Takes a \c FLEXProperty and a type (ie \c NSUInteger or \c id) and an Ivar name string to set the Ivar.
+#define FLEXPropertySetterWithIvar(FLEXProperty, ivarName, type) [FLEXProperty \
+    setterWithImplementation:imp_implementationWithBlock(^(id self, type value) { \
+        [self setIvarByName:ivarName value:&value size:sizeof(type)]; \
+    }) \
+];
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProperty.m

@@ -0,0 +1,295 @@
+//
+//  FLEXProperty.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXProperty.h"
+#import "FLEXPropertyAttributes.h"
+#import "FLEXMethodBase.h"
+#import "FLEXRuntimeUtility.h"
+#include <dlfcn.h>
+
+
+@interface FLEXProperty () {
+    NSString *_flex_description;
+}
+@property (nonatomic          ) BOOL uniqueCheckFlag;
+@property (nonatomic, readonly) Class cls;
+@end
+
+@implementation FLEXProperty
+@synthesize multiple = _multiple;
+@synthesize imageName = _imageName;
+@synthesize imagePath = _imagePath;
+
+#pragma mark Initializers
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
++ (instancetype)property:(objc_property_t)property {
+    return [[self alloc] initWithProperty:property onClass:nil];
+}
+
++ (instancetype)property:(objc_property_t)property onClass:(Class)cls {
+    return [[self alloc] initWithProperty:property onClass:cls];
+}
+
++ (instancetype)named:(NSString *)name onClass:(Class)cls {
+    objc_property_t _Nullable property = class_getProperty(cls, name.UTF8String);
+    NSAssert(property, @"Cannot find property with name %@ on class %@", name, cls);
+    return [self property:property onClass:cls];
+}
+
++ (instancetype)propertyWithName:(NSString *)name attributes:(FLEXPropertyAttributes *)attributes {
+    return [[self alloc] initWithName:name attributes:attributes];
+}
+
+- (id)initWithProperty:(objc_property_t)property onClass:(Class)cls {
+    NSParameterAssert(property);
+    
+    self = [super init];
+    if (self) {
+        _objc_property = property;
+        _attributes    = [FLEXPropertyAttributes attributesForProperty:property];
+        _name          = @(property_getName(property) ?: "(nil)");
+        _cls           = cls;
+        
+        if (!_attributes) [NSException raise:NSInternalInconsistencyException format:@"Error retrieving property attributes"];
+        if (!_name) [NSException raise:NSInternalInconsistencyException format:@"Error retrieving property name"];
+        
+        [self examine];
+    }
+    
+    return self;
+}
+
+- (id)initWithName:(NSString *)name attributes:(FLEXPropertyAttributes *)attributes {
+    NSParameterAssert(name); NSParameterAssert(attributes);
+    
+    self = [super init];
+    if (self) {
+        _attributes    = attributes;
+        _name          = name;
+        
+        [self examine];
+    }
+    
+    return self;
+}
+
+#pragma mark Private
+
+- (void)examine {
+    if (self.attributes.typeEncoding.length) {
+        _type = (FLEXTypeEncoding)[self.attributes.typeEncoding characterAtIndex:0];
+    }
+
+    // Return the given selector if the class responds to it
+    Class cls = _cls;
+    SEL (^selectorIfValid)(SEL) = ^SEL(SEL sel) {
+        if (!sel || !cls) return nil;
+        return [cls instancesRespondToSelector:sel] ? sel : nil;
+    };
+
+    SEL customGetter = self.attributes.customGetter;
+    SEL customSetter = self.attributes.customSetter;
+    SEL defaultGetter = NSSelectorFromString(self.name);
+    SEL defaultSetter = NSSelectorFromString([NSString
+        stringWithFormat:@"set%c%@:",
+        (char)toupper([self.name characterAtIndex:0]),
+        [self.name substringFromIndex:1]
+    ]);
+
+    // Check if the likely getters/setters exist
+    SEL validGetter = selectorIfValid(customGetter) ?: selectorIfValid(defaultGetter);
+    SEL validSetter = selectorIfValid(customSetter) ?: selectorIfValid(defaultSetter);
+    _likelyGetterExists = validGetter != nil;
+    _likelySetterExists = validSetter != nil;
+
+    // Assign likely getters and setters to the valid one,
+    // or the default, regardless of whether the default exists
+    _likelyGetter = validGetter ?: defaultGetter;
+    _likelySetter = validSetter ?: defaultSetter;
+    _likelyGetterString = NSStringFromSelector(_likelyGetter);
+    _likelySetterString = NSStringFromSelector(_likelySetter);
+
+    _isClassProperty = _cls ? class_isMetaClass(_cls) : NO;
+    
+    _likelyIvarName = _isClassProperty ? nil : (
+        self.attributes.backingIvar ?: [@"_" stringByAppendingString:_name]
+    );
+}
+
+#pragma mark Overrides
+
+- (NSString *)description {
+    if (!_flex_description) {
+        NSString *readableType = [FLEXRuntimeUtility readableTypeForEncoding:self.attributes.typeEncoding];
+        _flex_description = [FLEXRuntimeUtility appendName:self.name toType:readableType];
+    }
+
+    return _flex_description;
+}
+
+- (NSString *)debugDescription {
+    return [NSString stringWithFormat:@"<%@ name=%@, property=%p, attributes:\n\t%@\n>",
+            NSStringFromClass(self.class), self.name, self.objc_property, self.attributes];
+}
+
+#pragma mark Public
+
+- (objc_property_attribute_t *)copyAttributesList:(unsigned int *)attributesCount {
+    if (self.objc_property) {
+        return property_copyAttributeList(self.objc_property, attributesCount);
+    } else {
+        return [self.attributes copyAttributesList:attributesCount];
+    }
+}
+
+- (void)replacePropertyOnClass:(Class)cls {
+    class_replaceProperty(cls, self.name.UTF8String, self.attributes.list, (unsigned int)self.attributes.count);
+}
+
+- (void)computeSymbolInfo:(BOOL)forceBundle {
+    Dl_info exeInfo;
+    if (dladdr(_objc_property, &exeInfo)) {
+        _imagePath = exeInfo.dli_fname ? @(exeInfo.dli_fname) : nil;
+    }
+    
+    if ((!_multiple || !_uniqueCheckFlag) && _cls) {
+        _multiple = _objc_property != class_getProperty(_cls, self.name.UTF8String);
+
+        if (_multiple || forceBundle) {
+            NSString *path = _imagePath.stringByDeletingLastPathComponent;
+            _imageName = [NSBundle bundleWithPath:path].executablePath.lastPathComponent;
+        }
+    }
+}
+
+- (BOOL)multiple {
+    [self computeSymbolInfo:NO];
+    return _multiple;
+}
+
+- (NSString *)imagePath {
+    [self computeSymbolInfo:YES];
+    return _imagePath;
+}
+
+- (NSString *)imageName {
+    [self computeSymbolInfo:YES];
+    return _imageName;
+}
+
+- (BOOL)likelyIvarExists {
+    if (_likelyIvarName && _cls) {
+        return class_getInstanceVariable(_cls, _likelyIvarName.UTF8String) != nil;
+    }
+    
+    return NO;
+}
+
+- (NSString *)fullDescription {
+    NSMutableArray<NSString *> *attributesStrings = [NSMutableArray new];
+    FLEXPropertyAttributes *attributes = self.attributes;
+
+    // Atomicity
+    if (attributes.isNonatomic) {
+        [attributesStrings addObject:@"nonatomic"];
+    } else {
+        [attributesStrings addObject:@"atomic"];
+    }
+
+    // Storage
+    if (attributes.isRetained) {
+        [attributesStrings addObject:@"strong"];
+    } else if (attributes.isCopy) {
+        [attributesStrings addObject:@"copy"];
+    } else if (attributes.isWeak) {
+        [attributesStrings addObject:@"weak"];
+    } else {
+        [attributesStrings addObject:@"assign"];
+    }
+
+    // Mutability
+    if (attributes.isReadOnly) {
+        [attributesStrings addObject:@"readonly"];
+    } else {
+        [attributesStrings addObject:@"readwrite"];
+    }
+    
+    // Class or not
+    if (self.isClassProperty) {
+        [attributesStrings addObject:@"class"];
+    }
+
+    // Custom getter/setter
+    SEL customGetter = attributes.customGetter;
+    SEL customSetter = attributes.customSetter;
+    if (customGetter) {
+        [attributesStrings addObject:[NSString stringWithFormat:@"getter=%s", sel_getName(customGetter)]];
+    }
+    if (customSetter) {
+        [attributesStrings addObject:[NSString stringWithFormat:@"setter=%s", sel_getName(customSetter)]];
+    }
+
+    NSString *attributesString = [attributesStrings componentsJoinedByString:@", "];
+    return [NSString stringWithFormat:@"@property (%@) %@", attributesString, self.description];
+}
+
+- (id)getValue:(id)target {
+    if (!target) return nil;
+    
+    // We don't care about checking dynamically whether the getter
+    // _now_ exists on this object. If the getter doesn't exist
+    // when this property is initialized, it will never call it.
+    // Just re-create the property object if you need to call it.
+    if (self.likelyGetterExists) {
+        BOOL objectIsClass = object_isClass(target);
+        BOOL instanceAndInstanceProperty = !objectIsClass && !self.isClassProperty;
+        BOOL classAndClassProperty = objectIsClass && self.isClassProperty;
+
+        if (instanceAndInstanceProperty || classAndClassProperty) {
+            return [FLEXRuntimeUtility performSelector:self.likelyGetter onObject:target];
+        }
+    }
+
+    return nil;
+}
+
+- (id)getPotentiallyUnboxedValue:(id)target {
+    if (!target) return nil;
+
+    return [FLEXRuntimeUtility
+        potentiallyUnwrapBoxedPointer:[self getValue:target]
+        type:self.attributes.typeEncoding.UTF8String
+    ];
+}
+
+#pragma mark Suggested getters and setters
+
+- (FLEXMethodBase *)getterWithImplementation:(IMP)implementation {
+    NSString *types        = [NSString stringWithFormat:@"%@%s%s", self.attributes.typeEncoding, @encode(id), @encode(SEL)];
+    NSString *name         = [NSString stringWithFormat:@"%@", self.name];
+    FLEXMethodBase *getter = [FLEXMethodBase buildMethodNamed:name withTypes:types implementation:implementation];
+    return getter;
+}
+
+- (FLEXMethodBase *)setterWithImplementation:(IMP)implementation {
+    NSString *types        = [NSString stringWithFormat:@"%s%s%s%@", @encode(void), @encode(id), @encode(SEL), self.attributes.typeEncoding];
+    NSString *name         = [NSString stringWithFormat:@"set%@:", self.name.capitalizedString];
+    FLEXMethodBase *setter = [FLEXMethodBase buildMethodNamed:name withTypes:types implementation:implementation];
+    return setter;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXPropertyAttributes.h

@@ -0,0 +1,110 @@
+//
+//  FLEXPropertyAttributes.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/5/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import <objc/runtime.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark FLEXPropertyAttributes
+
+/// See \e FLEXRuntimeUtilitiy.h for valid string tokens.
+/// See this link on how to construct a proper attributes string:
+/// https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html
+@interface FLEXPropertyAttributes : NSObject <NSCopying, NSMutableCopying> {
+// These are necessary for the mutable subclass to function
+@protected
+    NSUInteger _count;
+    NSString *_string, *_backingIvar, *_typeEncoding, *_oldTypeEncoding, *_fullDeclaration;
+    NSDictionary *_dictionary;
+    objc_property_attribute_t *_list;
+    SEL _customGetter, _customSetter;
+    BOOL _isReadOnly, _isCopy, _isRetained, _isNonatomic, _isDynamic, _isWeak, _isGarbageCollectable;
+}
+
++ (instancetype)attributesForProperty:(objc_property_t)property;
+/// @warning Raises an exception if \e attributes is invalid, \c nil, or contains unsupported keys.
++ (instancetype)attributesFromDictionary:(NSDictionary *)attributes;
+
+/// Copies the attributes list to a buffer you must \c free() yourself.
+/// Use \c list instead if you do not need more control over the lifetime of the list.
+/// @param attributesCountOut the number of attributes is returned in this parameter.
+- (objc_property_attribute_t *)copyAttributesList:(nullable unsigned int *)attributesCountOut;
+
+/// The number of property attributes.
+@property (nonatomic, readonly) NSUInteger count;
+/// For use with \c class_replaceProperty and the like.
+@property (nonatomic, readonly) objc_property_attribute_t *list;
+/// The string value of the property attributes.
+@property (nonatomic, readonly) NSString *string;
+/// A human-readable version of the property attributes.
+@property (nonatomic, readonly) NSString *fullDeclaration;
+/// A dictionary of the property attributes.
+/// Values are either a string or \c YES. Boolean attributes
+/// which are false will not be present in the dictionary.
+@property (nonatomic, readonly) NSDictionary *dictionary;
+
+/// The name of the instance variable backing the property.
+@property (nonatomic, readonly, nullable) NSString *backingIvar;
+/// The type encoding of the property.
+@property (nonatomic, readonly, nullable) NSString *typeEncoding;
+/// The \e old type encoding of the property.
+@property (nonatomic, readonly, nullable) NSString *oldTypeEncoding;
+/// The property's custom getter, if any.
+@property (nonatomic, readonly, nullable) SEL customGetter;
+/// The property's custom setter, if any.
+@property (nonatomic, readonly, nullable) SEL customSetter;
+/// The property's custom getter as a string, if any.
+@property (nonatomic, readonly, nullable) NSString *customGetterString;
+/// The property's custom setter as a string, if any.
+@property (nonatomic, readonly, nullable) NSString *customSetterString;
+
+@property (nonatomic, readonly) BOOL isReadOnly;
+@property (nonatomic, readonly) BOOL isCopy;
+@property (nonatomic, readonly) BOOL isRetained;
+@property (nonatomic, readonly) BOOL isNonatomic;
+@property (nonatomic, readonly) BOOL isDynamic;
+@property (nonatomic, readonly) BOOL isWeak;
+@property (nonatomic, readonly) BOOL isGarbageCollectable;
+
+@end
+
+
+#pragma mark FLEXPropertyAttributes
+@interface FLEXMutablePropertyAttributes : FLEXPropertyAttributes
+
+/// Creates and returns an empty property attributes object.
++ (instancetype)attributes;
+
+/// The name of the instance variable backing the property.
+@property (nonatomic, nullable) NSString *backingIvar;
+/// The type encoding of the property.
+@property (nonatomic, nullable) NSString *typeEncoding;
+/// The \e old type encoding of the property.
+@property (nonatomic, nullable) NSString *oldTypeEncoding;
+/// The property's custom getter, if any.
+@property (nonatomic, nullable) SEL customGetter;
+/// The property's custom setter, if any.
+@property (nonatomic, nullable) SEL customSetter;
+
+@property (nonatomic) BOOL isReadOnly;
+@property (nonatomic) BOOL isCopy;
+@property (nonatomic) BOOL isRetained;
+@property (nonatomic) BOOL isNonatomic;
+@property (nonatomic) BOOL isDynamic;
+@property (nonatomic) BOOL isWeak;
+@property (nonatomic) BOOL isGarbageCollectable;
+
+/// A more convenient method of setting the \c typeEncoding property.
+/// @discussion This will not work for complex types like structs and primitive pointers.
+- (void)setTypeEncodingChar:(char)type;
+
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXPropertyAttributes.m

@@ -0,0 +1,376 @@
+//
+//  FLEXPropertyAttributes.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/5/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXPropertyAttributes.h"
+#import "FLEXRuntimeUtility.h"
+#import "NSString+ObjcRuntime.h"
+#import "NSDictionary+ObjcRuntime.h"
+
+
+#pragma mark FLEXPropertyAttributes
+
+@interface FLEXPropertyAttributes ()
+
+@property (nonatomic) NSString *backingIvar;
+@property (nonatomic) NSString *typeEncoding;
+@property (nonatomic) NSString *oldTypeEncoding;
+@property (nonatomic) SEL customGetter;
+@property (nonatomic) SEL customSetter;
+@property (nonatomic) BOOL isReadOnly;
+@property (nonatomic) BOOL isCopy;
+@property (nonatomic) BOOL isRetained;
+@property (nonatomic) BOOL isNonatomic;
+@property (nonatomic) BOOL isDynamic;
+@property (nonatomic) BOOL isWeak;
+@property (nonatomic) BOOL isGarbageCollectable;
+
+- (NSString *)buildFullDeclaration;
+
+@end
+
+@implementation FLEXPropertyAttributes
+@synthesize list = _list;
+
+#pragma mark Initializers
+
++ (instancetype)attributesForProperty:(objc_property_t)property {
+    return [self attributesFromDictionary:[NSDictionary attributesDictionaryForProperty:property]];
+}
+
++ (instancetype)attributesFromDictionary:(NSDictionary *)attributes {
+    return [[self alloc] initWithAttributesDictionary:attributes];
+}
+
+- (id)initWithAttributesDictionary:(NSDictionary *)attributes {
+    NSParameterAssert(attributes);
+    
+    self = [super init];
+    if (self) {
+        _dictionary           = attributes;
+        _string               = attributes.propertyAttributesString;
+        _count                = attributes.count;
+        _typeEncoding         = attributes[kFLEXPropertyAttributeKeyTypeEncoding];
+        _backingIvar          = attributes[kFLEXPropertyAttributeKeyBackingIvarName];
+        _oldTypeEncoding      = attributes[kFLEXPropertyAttributeKeyOldStyleTypeEncoding];
+        _customGetterString   = attributes[kFLEXPropertyAttributeKeyCustomGetter];
+        _customSetterString   = attributes[kFLEXPropertyAttributeKeyCustomSetter];
+        _customGetter         = NSSelectorFromString(_customGetterString);
+        _customSetter         = NSSelectorFromString(_customSetterString);
+        _isReadOnly           = attributes[kFLEXPropertyAttributeKeyReadOnly] != nil;
+        _isCopy               = attributes[kFLEXPropertyAttributeKeyCopy] != nil;
+        _isRetained           = attributes[kFLEXPropertyAttributeKeyRetain] != nil;
+        _isNonatomic          = attributes[kFLEXPropertyAttributeKeyNonAtomic] != nil;
+        _isWeak               = attributes[kFLEXPropertyAttributeKeyWeak] != nil;
+        _isGarbageCollectable = attributes[kFLEXPropertyAttributeKeyGarbageCollectable] != nil;
+
+        _fullDeclaration = [self buildFullDeclaration];
+    }
+    
+    return self;
+}
+
+#pragma mark Misc
+
+- (NSString *)description {
+    return [NSString
+        stringWithFormat:@"<%@ \"%@\", ivar=%@, readonly=%d, nonatomic=%d, getter=%@, setter=%@>",
+        NSStringFromClass(self.class),
+        self.string,
+        self.backingIvar ?: @"none",
+        self.isReadOnly,
+        self.isNonatomic,
+        NSStringFromSelector(self.customGetter) ?: @"none",
+        NSStringFromSelector(self.customSetter) ?: @"none"
+    ];
+}
+
+- (objc_property_attribute_t *)copyAttributesList:(unsigned int *)attributesCount {
+    NSDictionary *attrs = self.string.propertyAttributes;
+    objc_property_attribute_t *propertyAttributes = malloc(attrs.count * sizeof(objc_property_attribute_t));
+
+    if (attributesCount) {
+        *attributesCount = (unsigned int)attrs.count;
+    }
+    
+    NSUInteger i = 0;
+    for (NSString *key in attrs.allKeys) {
+        FLEXPropertyAttribute c = (FLEXPropertyAttribute)[key characterAtIndex:0];
+        switch (c) {
+            case FLEXPropertyAttributeTypeEncoding: {
+                objc_property_attribute_t pa = {
+                    kFLEXPropertyAttributeKeyTypeEncoding.UTF8String,
+                    self.typeEncoding.UTF8String
+                };
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeBackingIvarName: {
+                objc_property_attribute_t pa = {
+                    kFLEXPropertyAttributeKeyBackingIvarName.UTF8String,
+                    self.backingIvar.UTF8String
+                };
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeCopy: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyCopy.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeCustomGetter: {
+                objc_property_attribute_t pa = {
+                    kFLEXPropertyAttributeKeyCustomGetter.UTF8String,
+                    NSStringFromSelector(self.customGetter).UTF8String ?: ""
+                };
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeCustomSetter: {
+                objc_property_attribute_t pa = {
+                    kFLEXPropertyAttributeKeyCustomSetter.UTF8String,
+                    NSStringFromSelector(self.customSetter).UTF8String ?: ""
+                };
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeDynamic: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyDynamic.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeGarbageCollectible: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyGarbageCollectable.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeNonAtomic: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyNonAtomic.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeOldTypeEncoding: {
+                objc_property_attribute_t pa = {
+                    kFLEXPropertyAttributeKeyOldStyleTypeEncoding.UTF8String,
+                    self.oldTypeEncoding.UTF8String ?: ""
+                };
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeReadOnly: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyReadOnly.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeRetain: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyRetain.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+            case FLEXPropertyAttributeWeak: {
+                objc_property_attribute_t pa = {kFLEXPropertyAttributeKeyWeak.UTF8String, ""};
+                propertyAttributes[i] = pa;
+                break;
+            }
+        }
+        i++;
+    }
+    
+    return propertyAttributes;
+}
+
+- (objc_property_attribute_t *)list {
+    if (!_list) {
+        _list = [self copyAttributesList:nil];
+    }
+
+    return _list;
+}
+
+- (NSString *)buildFullDeclaration {
+    NSMutableString *decl = [NSMutableString new];
+
+    [decl appendFormat:@"%@, ", _isNonatomic ? @"nonatomic" : @"atomic"];
+    [decl appendFormat:@"%@, ", _isReadOnly ? @"readonly" : @"readwrite"];
+
+    BOOL noExplicitMemorySemantics = YES;
+    if (_isCopy) { noExplicitMemorySemantics = NO;
+        [decl appendString:@"copy, "];
+    }
+    if (_isRetained) { noExplicitMemorySemantics = NO;
+        [decl appendString:@"strong, "];
+    }
+    if (_isWeak) { noExplicitMemorySemantics = NO;
+        [decl appendString:@"weak, "];
+    }
+
+    if ([_typeEncoding hasPrefix:@"@"] && noExplicitMemorySemantics) {
+        // *probably* strong if this is an object; strong is the default.
+        [decl appendString:@"strong, "];
+    } else if (noExplicitMemorySemantics) {
+        // *probably* assign if this is not an object
+        [decl appendString:@"assign, "];
+    }
+
+    if (_customGetter) {
+        [decl appendFormat:@"getter=%@, ", NSStringFromSelector(_customGetter)];
+    }
+    if (_customSetter) {
+        [decl appendFormat:@"setter=%@, ", NSStringFromSelector(_customSetter)];
+    }
+
+    [decl deleteCharactersInRange:NSMakeRange(decl.length-2, 2)];
+    return decl.copy;
+}
+
+- (void)dealloc {
+    if (_list) {
+        free(_list);
+        _list = nil;
+    }
+}
+
+#pragma mark Copying
+
+- (id)copyWithZone:(NSZone *)zone {
+    return [[FLEXPropertyAttributes class] attributesFromDictionary:self.dictionary];
+}
+
+- (id)mutableCopyWithZone:(NSZone *)zone {
+    return [[FLEXMutablePropertyAttributes class] attributesFromDictionary:self.dictionary];
+}
+
+@end
+
+
+
+#pragma mark FLEXMutablePropertyAttributes
+
+@interface FLEXMutablePropertyAttributes ()
+@property (nonatomic) BOOL countDelta;
+@property (nonatomic) BOOL stringDelta;
+@property (nonatomic) BOOL dictDelta;
+@property (nonatomic) BOOL listDelta;
+@property (nonatomic) BOOL declDelta;
+@end
+
+#define PropertyWithDeltaFlag(type, name, Name) @dynamic name; \
+- (void)set ## Name:(type)name { \
+    if (name != _ ## name) { \
+        _countDelta = _stringDelta = _dictDelta = _listDelta = _declDelta = YES; \
+        _ ## name = name; \
+    } \
+}
+
+@implementation FLEXMutablePropertyAttributes
+
+PropertyWithDeltaFlag(NSString *, backingIvar, BackingIvar);
+PropertyWithDeltaFlag(NSString *, typeEncoding, TypeEncoding);
+PropertyWithDeltaFlag(NSString *, oldTypeEncoding, OldTypeEncoding);
+PropertyWithDeltaFlag(SEL, customGetter, CustomGetter);
+PropertyWithDeltaFlag(SEL, customSetter, CustomSetter);
+PropertyWithDeltaFlag(BOOL, isReadOnly, IsReadOnly);
+PropertyWithDeltaFlag(BOOL, isCopy, IsCopy);
+PropertyWithDeltaFlag(BOOL, isRetained, IsRetained);
+PropertyWithDeltaFlag(BOOL, isNonatomic, IsNonatomic);
+PropertyWithDeltaFlag(BOOL, isDynamic, IsDynamic);
+PropertyWithDeltaFlag(BOOL, isWeak, IsWeak);
+PropertyWithDeltaFlag(BOOL, isGarbageCollectable, IsGarbageCollectable);
+
++ (instancetype)attributes {
+    return [self new];
+}
+
+- (void)setTypeEncodingChar:(char)type {
+    self.typeEncoding = [NSString stringWithFormat:@"%c", type];
+}
+
+- (NSUInteger)count {
+    // Recalculate attribute count after mutations
+    if (self.countDelta) {
+        self.countDelta = NO;
+        _count = self.dictionary.count;
+    }
+
+    return _count;
+}
+
+- (objc_property_attribute_t *)list {
+    // Regenerate list after mutations
+    if (self.listDelta) {
+        self.listDelta = NO;
+        if (_list) {
+            free(_list);
+            _list = nil;
+        }
+    }
+
+    // Super will generate the list if it isn't set
+    return super.list;
+}
+
+- (NSString *)string {
+    // Regenerate string after mutations
+    if (self.stringDelta || !_string) {
+        self.stringDelta = NO;
+        _string = self.dictionary.propertyAttributesString;
+    }
+
+    return _string;
+}
+
+- (NSDictionary *)dictionary {
+    // Regenerate dictionary after mutations
+    if (self.dictDelta || !_dictionary) {
+        // _stringa nd _dictionary depend on each other,
+        // so we must generate ONE by hand using our properties.
+        // We arbitrarily choose to generate the dictionary.
+        NSMutableDictionary *attrs = [NSMutableDictionary new];
+        if (self.typeEncoding)
+            attrs[kFLEXPropertyAttributeKeyTypeEncoding]         = self.typeEncoding;
+        if (self.backingIvar)
+            attrs[kFLEXPropertyAttributeKeyBackingIvarName]      = self.backingIvar;
+        if (self.oldTypeEncoding)
+            attrs[kFLEXPropertyAttributeKeyOldStyleTypeEncoding] = self.oldTypeEncoding;
+        if (self.customGetter)
+            attrs[kFLEXPropertyAttributeKeyCustomGetter]         = NSStringFromSelector(self.customGetter);
+        if (self.customSetter)
+            attrs[kFLEXPropertyAttributeKeyCustomSetter]         = NSStringFromSelector(self.customSetter);
+
+        if (self.isReadOnly)           attrs[kFLEXPropertyAttributeKeyReadOnly] = @YES;
+        if (self.isCopy)               attrs[kFLEXPropertyAttributeKeyCopy] = @YES;
+        if (self.isRetained)           attrs[kFLEXPropertyAttributeKeyRetain] = @YES;
+        if (self.isNonatomic)          attrs[kFLEXPropertyAttributeKeyNonAtomic] = @YES;
+        if (self.isDynamic)            attrs[kFLEXPropertyAttributeKeyDynamic] = @YES;
+        if (self.isWeak)               attrs[kFLEXPropertyAttributeKeyWeak] = @YES;
+        if (self.isGarbageCollectable) attrs[kFLEXPropertyAttributeKeyGarbageCollectable] = @YES;
+
+        _dictionary = attrs.copy;
+    }
+
+    return _dictionary;
+}
+
+- (NSString *)fullDeclaration {
+    if (self.declDelta || !_fullDeclaration) {
+        _declDelta = NO;
+        _fullDeclaration = [self buildFullDeclaration];
+    }
+
+    return _fullDeclaration;
+}
+
+- (NSString *)customGetterString {
+    return _customGetter ? NSStringFromSelector(_customGetter) : nil;
+}
+
+- (NSString *)customSetterString {
+    return _customSetter ? NSStringFromSelector(_customSetter) : nil;
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProtocol.h

@@ -0,0 +1,73 @@
+//
+//  FLEXProtocol.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXRuntimeConstants.h"
+@class FLEXProperty, FLEXMethodDescription;
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark FLEXProtocol
+@interface FLEXProtocol : NSObject
+
+/// Every protocol registered with the runtime.
++ (NSArray<FLEXProtocol *> *)allProtocols;
++ (instancetype)protocol:(Protocol *)protocol;
+
+/// The underlying protocol data structure.
+@property (nonatomic, readonly) Protocol *objc_protocol;
+
+/// The name of the protocol.
+@property (nonatomic, readonly) NSString *name;
+/// The required methods of the protocol, if any. This includes property getters and setters.
+@property (nonatomic, readonly) NSArray<FLEXMethodDescription *> *requiredMethods;
+/// The optional methods of the protocol, if any. This includes property getters and setters.
+@property (nonatomic, readonly) NSArray<FLEXMethodDescription *> *optionalMethods;
+/// All protocols that this protocol conforms to, if any.
+@property (nonatomic, readonly) NSArray<FLEXProtocol *> *protocols;
+/// The full path of the image that contains this protocol definition,
+/// or \c nil if this protocol was probably defined at runtime.
+@property (nonatomic, readonly, nullable) NSString *imagePath;
+
+/// The properties in the protocol, if any. \c nil on iOS 10+ 
+@property (nonatomic, readonly, nullable) NSArray<FLEXProperty *> *properties API_DEPRECATED("Use the more specific accessors below", ios(2.0, 10.0));
+
+/// The required properties in the protocol, if any.
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *requiredProperties API_AVAILABLE(ios(10.0));
+/// The optional properties in the protocol, if any.
+@property (nonatomic, readonly) NSArray<FLEXProperty *> *optionalProperties API_AVAILABLE(ios(10.0));
+
+/// For internal use
+@property (nonatomic) id tag;
+
+/// Not to be confused with \c -conformsToProtocol:, which refers to the current
+/// \c FLEXProtocol instance and not the underlying \c Protocol object.
+- (BOOL)conformsTo:(Protocol *)protocol;
+
+@end
+
+
+#pragma mark Method descriptions
+@interface FLEXMethodDescription : NSObject
+
++ (instancetype)description:(struct objc_method_description)description;
++ (instancetype)description:(struct objc_method_description)description instance:(BOOL)isInstance;
+
+/// The underlying method description data structure.
+@property (nonatomic, readonly) struct objc_method_description objc_description;
+/// The method's selector.
+@property (nonatomic, readonly) SEL selector;
+/// The method's type encoding.
+@property (nonatomic, readonly) NSString *typeEncoding;
+/// The method's return type.
+@property (nonatomic, readonly) FLEXTypeEncoding returnType;
+/// \c YES if this is an instance method, \c NO if it is a class method, or \c nil if unspecified
+@property (nonatomic, readonly) NSNumber *instance;
+@end
+
+NS_ASSUME_NONNULL_END

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProtocol.m

@@ -0,0 +1,212 @@
+//
+//  FLEXProtocol.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 6/30/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXProtocol.h"
+#import "FLEXProperty.h"
+#import "FLEXRuntimeUtility.h"
+#import "NSArray+FLEX.h"
+#include <dlfcn.h>
+
+@implementation FLEXProtocol
+
+#pragma mark Initializers
+
++ (NSArray *)allProtocols {
+    unsigned int prcount;
+    Protocol *__unsafe_unretained*protocols = objc_copyProtocolList(&prcount);
+    
+    NSMutableArray *all = [NSMutableArray new];
+    for(NSUInteger i = 0; i < prcount; i++)
+        [all addObject:[self protocol:protocols[i]]];
+    
+    free(protocols);
+    return all;
+}
+
++ (instancetype)protocol:(Protocol *)protocol {
+    return [[self alloc] initWithProtocol:protocol];
+}
+
+- (id)initWithProtocol:(Protocol *)protocol {
+    NSParameterAssert(protocol);
+    
+    self = [super init];
+    if (self) {
+        _objc_protocol = protocol;
+        [self examine];
+    }
+    
+    return self;
+}
+
+#pragma mark Other
+
+- (NSString *)description {
+    return self.name;
+}
+
+- (NSString *)debugDescription {
+    return [NSString stringWithFormat:@"<%@ name=%@, %lu properties, %lu required methods, %lu optional methods, %lu protocols>",
+            NSStringFromClass(self.class), self.name, (unsigned long)self.properties.count,
+            (unsigned long)self.requiredMethods.count, (unsigned long)self.optionalMethods.count, (unsigned long)self.protocols.count];
+}
+
+- (void)examine {
+    _name = @(protocol_getName(self.objc_protocol));
+    
+    // imagePath
+    Dl_info exeInfo;
+    if (dladdr((__bridge const void *)(_objc_protocol), &exeInfo)) {
+        _imagePath = exeInfo.dli_fname ? @(exeInfo.dli_fname) : nil;
+    }
+    
+    // Conformances and methods //
+    
+    unsigned int pccount, mdrcount, mdocount;
+    struct objc_method_description *objcrMethods, *objcoMethods;
+    Protocol *protocol = _objc_protocol;
+    Protocol * __unsafe_unretained *protocols = protocol_copyProtocolList(protocol, &pccount);
+    
+    // Protocols
+    _protocols = [NSArray flex_forEachUpTo:pccount map:^id(NSUInteger i) {
+        return [FLEXProtocol protocol:protocols[i]];
+    }];
+    free(protocols);
+    
+    // Required instance methods
+    objcrMethods = protocol_copyMethodDescriptionList(protocol, YES, YES, &mdrcount);
+    NSArray *rMethods = [NSArray flex_forEachUpTo:mdrcount map:^id(NSUInteger i) {
+        return [FLEXMethodDescription description:objcrMethods[i] instance:YES];
+    }];
+    free(objcrMethods);
+    
+    // Required class methods 
+    objcrMethods = protocol_copyMethodDescriptionList(protocol, YES, NO, &mdrcount);
+    _requiredMethods = [[NSArray flex_forEachUpTo:mdrcount map:^id(NSUInteger i) {
+        return [FLEXMethodDescription description:objcrMethods[i] instance:NO];
+    }] arrayByAddingObjectsFromArray:rMethods];
+    free(objcrMethods);
+    
+    // Optional instance methods
+    objcoMethods = protocol_copyMethodDescriptionList(protocol, NO, YES, &mdocount);
+    NSArray *oMethods = [NSArray flex_forEachUpTo:mdocount map:^id(NSUInteger i) {
+        return [FLEXMethodDescription description:objcoMethods[i] instance:YES];
+    }];
+    free(objcoMethods);
+    
+    // Optional class methods
+    objcoMethods = protocol_copyMethodDescriptionList(protocol, NO, NO, &mdocount);
+    _optionalMethods = [[NSArray flex_forEachUpTo:mdocount map:^id(NSUInteger i) {
+        return [FLEXMethodDescription description:objcoMethods[i] instance:NO];
+    }] arrayByAddingObjectsFromArray:oMethods];
+    free(objcoMethods);
+    
+    // Properties is a hassle because they didn't fix the API until iOS 10 //
+    
+    if (@available(iOS 10.0, *)) {
+        unsigned int prrcount, procount;
+        Class instance = [NSObject class], meta = objc_getMetaClass("NSObject");
+        
+        // Required class and instance properties //
+        
+        // Instance first
+        objc_property_t *rProps = protocol_copyPropertyList2(protocol, &prrcount, YES, YES);
+        NSArray *rProperties = [NSArray flex_forEachUpTo:prrcount map:^id(NSUInteger i) {
+            return [FLEXProperty property:rProps[i] onClass:instance];
+        }];
+        free(rProps);
+        
+        // Then class
+        rProps = protocol_copyPropertyList2(protocol, &prrcount, NO, YES);
+        _requiredProperties = [[NSArray flex_forEachUpTo:prrcount map:^id(NSUInteger i) {
+            return [FLEXProperty property:rProps[i] onClass:instance];
+        }] arrayByAddingObjectsFromArray:rProperties];
+        free(rProps);
+        
+        // Optional class and instance properties //
+        
+        // Instance first
+        objc_property_t *oProps = protocol_copyPropertyList2(protocol, &procount, YES, YES);
+        NSArray *oProperties = [NSArray flex_forEachUpTo:prrcount map:^id(NSUInteger i) {
+            return [FLEXProperty property:oProps[i] onClass:meta];
+        }];
+        free(oProps);
+        
+        // Then class
+        oProps = protocol_copyPropertyList2(protocol, &procount, NO, YES);
+        _optionalProperties = [[NSArray flex_forEachUpTo:procount map:^id(NSUInteger i) {
+            return [FLEXProperty property:oProps[i] onClass:meta];
+        }] arrayByAddingObjectsFromArray:oProperties];
+        free(oProps);
+        
+    } else {
+        unsigned int prcount;
+        objc_property_t *objcproperties = protocol_copyPropertyList(protocol, &prcount);
+        _properties = [NSArray flex_forEachUpTo:prcount map:^id(NSUInteger i) {
+            return [FLEXProperty property:objcproperties[i]];
+        }];
+        
+        _requiredProperties = @[];
+        _optionalProperties = @[];
+        
+        free(objcproperties);
+    }
+}
+
+- (BOOL)conformsTo:(Protocol *)protocol {
+    return protocol_conformsToProtocol(self.objc_protocol, protocol);
+}
+
+@end
+
+#pragma mark FLEXMethodDescription
+
+@implementation FLEXMethodDescription
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
++ (instancetype)description:(struct objc_method_description)description {
+    return [[self alloc] initWithDescription:description instance:nil];
+}
+
++ (instancetype)description:(struct objc_method_description)description instance:(BOOL)isInstance {
+    return [[self alloc] initWithDescription:description instance:@(isInstance)];
+}
+
+- (id)initWithDescription:(struct objc_method_description)md instance:(NSNumber *)instance {
+    NSParameterAssert(md.name != NULL);
+    
+    self = [super init];
+    if (self) {
+        _objc_description = md;
+        _selector         = md.name;
+        _typeEncoding     = @(md.types);
+        _returnType       = (FLEXTypeEncoding)[self.typeEncoding characterAtIndex:0];
+        _instance         = instance;
+    }
+    
+    return self;
+}
+
+- (NSString *)description {
+    return NSStringFromSelector(self.selector);
+}
+
+- (NSString *)debugDescription {
+    return [NSString stringWithFormat:@"<%@ name=%@, type=%@>",
+            NSStringFromClass(self.class), NSStringFromSelector(self.selector), self.typeEncoding];
+}
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProtocolBuilder.h

@@ -0,0 +1,41 @@
+//
+//  FLEXProtocolBuilder.h
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/4/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+@class FLEXProperty, FLEXProtocol, Protocol;
+
+@interface FLEXProtocolBuilder : NSObject
+
+/// Begins to construct a new protocol with the given name.
+/// @discussion You must register the protocol with the
+/// \c registerProtocol method before you can use it.
++ (instancetype)allocateProtocol:(NSString *)name;
+
+/// Adds a property to a protocol.
+/// @param property The property to add.
+/// @param isRequired Whether the property is required to implement the protocol.
+- (void)addProperty:(FLEXProperty *)property isRequired:(BOOL)isRequired;
+/// Adds a property to a protocol.
+/// @param selector The selector of the method to add.
+/// @param typeEncoding The type encoding of the method to add.
+/// @param isRequired Whether the method is required to implement the protocol.
+/// @param isInstanceMethod \c YES if the method is an instance method, \c NO if it is a class method.
+- (void)addMethod:(SEL)selector
+     typeEncoding:(NSString *)typeEncoding
+       isRequired:(BOOL)isRequired
+ isInstanceMethod:(BOOL)isInstanceMethod;
+/// Makes the recieving protocol conform to the given protocol.
+- (void)addProtocol:(Protocol *)protocol;
+
+/// Registers and returns the recieving protocol, which was previously under construction.
+- (FLEXProtocol *)registerProtocol;
+/// Whether the protocol is still under construction or already registered.
+@property (nonatomic, readonly) BOOL isRegistered;
+
+@end

Tweaks/FLEX/Utility/Runtime/Objc/Reflection/FLEXProtocolBuilder.m

@@ -0,0 +1,93 @@
+//
+//  FLEXProtocolBuilder.m
+//  FLEX
+//
+//  Derived from MirrorKit.
+//  Created by Tanner on 7/4/15.
+//  Copyright (c) 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXProtocolBuilder.h"
+#import "FLEXProtocol.h"
+#import "FLEXProperty.h"
+#import <objc/runtime.h>
+
+#define MutationAssertion(msg) if (self.isRegistered) { \
+    [NSException \
+        raise:NSInternalInconsistencyException \
+        format:msg \
+    ]; \
+}
+
+@interface FLEXProtocolBuilder ()
+@property (nonatomic) Protocol *workingProtocol;
+@property (nonatomic) NSString *name;
+@end
+
+@implementation FLEXProtocolBuilder
+
+- (id)init {
+    [NSException
+        raise:NSInternalInconsistencyException
+        format:@"Class instance should not be created with -init"
+    ];
+    return nil;
+}
+
+#pragma mark Initializers
++ (instancetype)allocateProtocol:(NSString *)name {
+    NSParameterAssert(name);
+    return [[self alloc] initWithProtocol:objc_allocateProtocol(name.UTF8String)];
+    
+}
+
+- (id)initWithProtocol:(Protocol *)protocol {
+    NSParameterAssert(protocol);
+    
+    self = [super init];
+    if (self) {
+        _workingProtocol = protocol;
+        _name = NSStringFromProtocol(self.workingProtocol);
+    }
+    
+    return self;
+}
+
+- (NSString *)description {
+    return [NSString stringWithFormat:@"<%@ name=%@, registered=%d>",
+            NSStringFromClass(self.class), self.name, self.isRegistered];
+}
+
+#pragma mark Building
+
+- (void)addProperty:(FLEXProperty *)property isRequired:(BOOL)isRequired {
+    MutationAssertion(@"Properties cannot be added once a protocol has been registered");
+
+    unsigned int count;
+    objc_property_attribute_t *attributes = [property copyAttributesList:&count];
+    protocol_addProperty(self.workingProtocol, property.name.UTF8String, attributes, count, isRequired, YES);
+    free(attributes);
+}
+
+- (void)addMethod:(SEL)selector
+    typeEncoding:(NSString *)typeEncoding
+       isRequired:(BOOL)isRequired
+ isInstanceMethod:(BOOL)isInstanceMethod {
+    MutationAssertion(@"Methods cannot be added once a protocol has been registered");
+    protocol_addMethodDescription(self.workingProtocol, selector, typeEncoding.UTF8String, isRequired, isInstanceMethod);
+}
+
+- (void)addProtocol:(Protocol *)protocol {
+    MutationAssertion(@"Protocols cannot be added once a protocol has been registered");
+    protocol_addProtocol(self.workingProtocol, protocol);
+}
+
+- (FLEXProtocol *)registerProtocol {
+    MutationAssertion(@"Protocol is already registered");
+    
+    _isRegistered = YES;
+    objc_registerProtocol(self.workingProtocol);
+    return [FLEXProtocol protocol:self.workingProtocol];
+}
+
+@end