- CALayer* maskLayer = [CALayer layer];
- maskLayer.frame = CGRectMake(0, 0, 100, 100);
- maskLayer.position = CGPointMake(0, 0);
- maskLayer.anchorPoint = CGPointMake(0,0);
- CGImageRef maskImage = [UIImage imageNamed:@"hole_mask.png"].CGImage;
- [maskLayer setContents:(id)maskImage];
- myImageView.layer.mask = maskLayer;