How to Mask an Image

- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {

CGImageRef maskRef = maskImage.CGImage; 

CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),

CGImageGetHeight(maskRef),

CGImageGetBitsPerComponent(maskRef),

CGImageGetBitsPerPixel(maskRef),

CGImageGetBytesPerRow(maskRef),

CGImageGetDataProvider(maskRef), NULL, false);

CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);

return [UIImage imageWithCGImage:masked];

}