Mask based CALayer hit testing

gistfile1.m

#import "CALayer_HitTestExtensions.h"

#import <objc/runtime.h>

static void *kHitMask;

@implementation CALayer (CALayer_HitTestExtensions)

- (NSUInteger)hitMask
    {
    return([objc_getAssociatedObject(self, &kHitMask) unsignedIntegerValue]);
    }

- (void)setHitMask:(NSUInteger)inHitMask
    {
    objc_setAssociatedObject(self, &kHitMask, [NSNumber numberWithUnsignedInteger:inHitMask], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

- (CALayer *)hitTest:(CGPoint)inPoint mask:(NSUInteger)inMask;
    {
    CALayer *theLayer = [self hitTest:inPoint];
    
    while (theLayer != NULL && theLayer != self)
        {
        if (inMask & theLayer.hitMask)
            {
            return(theLayer);
            }
            
        theLayer = [theLayer superlayer];
        }
    
    return(NULL);
    }

@end