mask image

gistfile1.m

- (UIImage*) maskImage:(UIImage *)image
              withMask:(UIImage *)maskImage
{
    CGImageRef imageRef = image.CGImage;
    CGImageRef maskRef = maskImage.CGImage;
    CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
                                        CGImageGetHeight(maskRef),
                                        CGImageGetBitsPerComponent(maskRef),
                                        CGImageGetBitsPerPixel(maskRef),
                                        CGImageGetBytesPerRow(maskRef),
                                        CGImageGetDataProvider(maskRef),
                                        NULL, // decode should be NULL
                                        FALSE // shouldInterpolate
                                        );
    CGImageRef masked = CGImageCreateWithMask(imageRef, mask);
    CGImageRelease(mask);
    UIImage *maskedImage = [UIImage imageWithCGImage:masked];
    CGImageRelease(masked);
    
    return maskedImage;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    UIImage *imageToCrop = [UIImage imageNamed:@"peggy.jpg"];
    CGRect rect = CGRectMake(615, 20, 220, 220);
    CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
    UIImage *image = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    
    UIImage *newImage = [self maskImage:image withMask:[UIImage imageNamed:@"mask.png"]];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:newImage];
    [self.view addSubview:imageView];
    
}