Add a mask to UIImage

Http://stackoverflow.com/questions/17448102/ios-masking-an-image-keeping-retina-scale-factor-in-account

I want to mask a image by passing another image as mask. I am able to mask the image and the resulting image doesn ' t look good. It's jagged at borders.

I guess the problem is related to retina graphics. The scale property for the images is different as:

1. The image from which I want to mask have a scale value 1. This image generally have a resolution greater than 1000x1000 pixels.
2. The image according to which I want the resulting image (image had black and white colors only) had scale value 2. This image is generally of resolution 300x300 pixels.

The resulting image has a scale value of 1.

The code I am using is:

+ (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);CGImageRelease(mask);UIImage *maskedImage = [UIImage imageWithCGImage:masked ];CGImageRelease(masked);return maskedImage;}

How can I get a masked image which follows retina scale?

Add a mask to UIImage