Trying to use ZKSwizzle

ZKSwizzle.m

@interface ZKHookClass : NSObject
- (id)forwardingTargetForSelector:(SEL)aSelector;
- (BOOL)respondsToSelector:(SEL)aSelector;
@end

@implementation ZKHookClass

- (id)forwardingTargetForSelector:(SEL) aSelector {
    NSLog(@"%@", NSStringFromSelector(aSelector));
    return _orig(id, aSelector);
}

- (BOOL)respondsToSelector:(SEL)aSelector {
    NSLog(@"%@", NSStringFromSelector(aSelector));
    return _orig(BOOL, aSelector);
}

@end
  
// then create a category on NSObject, and:
@implementation NSObject (ZKCategory)

+ (void)load
{
   // This now works for forwardingTargetForSelector: but 
   // goes into what appears to be a recursive death spiral with respondsToSelector: 
   _ZKSwizzle(ZKClass(ZKHookClass), self);
}
@end