Find the first responder by swizzeling methods of UIResponder

Find First Responder Swizzeling

// ************************************************************ //
// UIResponder+FirstResponder.h
// ************************************************************ //

@interface UIResponder (FirstResponder)

+ (UIResponder*)firstResponder;

@end

// ************************************************************ //
// UIResponder+FirstResponder.m
// ************************************************************ //

#import "NSObject+Swizzle.h" // <-- https://gist.github.com/vilanovi/688564548c904fd7b2d2

static NSHashTable *__instances = nil;

@implementation UIResponder (FirstResponder)

+ (UIResponder*)firstResponder
{
    id firstResponder = nil;
    
    NSHashTable *table = [__instances copy];
    
    for (UIResponder *responder in table)
    {
        if ([responder isFirstResponder])
        {
            firstResponder = responder;
            break;
        }
    }
    
    return firstResponder;
}

+ (void)load
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        __instances = [NSHashTable hashTableWithOptions:NSPointerFunctionsWeakMemory];
        [self swizzleSelector:@selector(init) withSelector:@selector(init_custom)];
    });
}

- (id)init_custom
{
    self = [self init_custom];
    if (self)
    {
        [__instances addObject:self];
    }
    return self;
}

@end