Mix-in protocol that forwards appearance methods to child view controllers

RLRAppearanceForwarding.h

/*
 RLRAppearanceForwarding.h
 
 Copyright ©2014 Kazki Miura. All rights reserved.
*/

#import <UIKit/UIKit.h>


@protocol RLRAppearanceForwarding <NSObject>
@optional
- (BOOL)isAppearanceForwardingEnabled; // Make it property >>>
- (void)setAppearanceForwardingEnabled:(BOOL)enabled;
@end

RLRAppearanceForwarding.m

/*
 RLRAppearanceForwarding.m
 
 Copyright ©2014 Kazki Miura. All rights reserved.
*/

#import "RLRAppearanceForwarding.h"
#import "REKit.h"


// Constants
static void *kLoadedKey = @"RLRAppearanceForwarding_loaded";
static void *kEnabledKey = @"RLRAppearanceForwarding_enabled";
static NSString *const kBlockKey = @"RLRAppearanceForwardingBlock";


@implementation UIViewController (RLRAppearanceForwarding)

+ (void)load
{
	@autoreleasepool {
		for (Class class in RESubclassesOfClass([UIViewController class], YES)) {
			if ([class conformsToProtocol:@protocol(RLRAppearanceForwarding)]
			&& ![[class superclass] conformsToProtocol:@protocol(RLRAppearanceForwarding)]
			&& ![[class associatedValueForKey:kLoadedKey] boolValue]
			){
				// Raise loaded flag
				[class setAssociatedValue:@(YES) forKey:kLoadedKey policy:OBJC_ASSOCIATION_RETAIN];
				
				#pragma mark └ -[class isAppearanceForwardingEnabled]
				RESetBlock(class, @selector(isAppearanceForwardingEnabled), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc) {
					// Return flag
					NSNumber *boolNum;
					boolNum = [vc associatedValueForKey:kEnabledKey];
					return (boolNum ? [boolNum boolValue] : YES);
				});
				
				#pragma mark └ -[class setAppearanceForwardingEnabled:]
				RESetBlock(class, @selector(setAppearanceForwardingEnabled:), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc, BOOL enabled) {
					// Set flag
					[vc setAssociatedValue:@(enabled) forKey:kEnabledKey policy:OBJC_ASSOCIATION_RETAIN];
				});
				
				#pragma mark └ -[class shouldAutomaticallyForwardAppearanceMethods]
				RESetBlock(class, @selector(shouldAutomaticallyForwardAppearanceMethods), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc) {
					return ![vc isAppearanceForwardingEnabled];
				});
				
				#pragma mark └ -[class viewWillAppear:]
				RESetBlock(class, @selector(viewWillAppear:), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc, BOOL animated) {
					// supermethod
					RESupermethod(nil, vc, animated);
					
					// Forward
					if ([vc isAppearanceForwardingEnabled]) {
						for (UIViewController *aChildViewController in vc.childViewControllers) {
							[aChildViewController beginAppearanceTransition:YES animated:animated];
						}
					}
				});
				
				#pragma mark └ -[class viewDidAppear:]
				RESetBlock(class, @selector(viewDidAppear:), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc, BOOL animated) {
					// supermethod
					RESupermethod(nil, vc, animated);
					
					// Forward
					if ([vc isAppearanceForwardingEnabled]) {
						[vc.childViewControllers makeObjectsPerformSelector:@selector(endAppearanceTransition)];
					}
				});
				
				#pragma mark └ -[class viewWillDisappear:]
				RESetBlock(class, @selector(viewWillDisappear:), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc, BOOL animated) {
					// supermethod
					RESupermethod(nil, vc, animated);
					
					// Forward
					if ([vc isAppearanceForwardingEnabled]) {
						for (UIViewController *aChildViewController in vc.childViewControllers) {
							[aChildViewController beginAppearanceTransition:NO animated:animated];
						}
					}
				});
				
				#pragma mark └ -[class viewDidDisappear:]
				RESetBlock(class, @selector(viewDidDisappear:), NO, kBlockKey, ^(UIViewController<RLRAppearanceForwarding> *vc, BOOL animated) {
					// supermethod
					RESupermethod(nil, vc, animated);
					
					// Forward
					if ([vc isAppearanceForwardingEnabled]) {
						[vc.childViewControllers makeObjectsPerformSelector:@selector(endAppearanceTransition)];
					}
				});
			}
		}
	}
}

@end