Xcode remove color from image programmatically?

Question

So I have an app where you move images around in certain positions and layer them. Its coming along well but an issue I keep running into is a lot of my images have white spaces around them (they use to be jpgs), the whitespace is always hexcode #FFFFFF pure whitespace, so I was wondering is there a way in objective-c to mask all of a hexcode in an image? I would manually edit the images but there are thousands of them from a third party. Any ideas?

Answer 1

I found this awesome method here that you can place in your current .h file:

+(UIImage *)changeWhiteColorTransparent: (UIImage *)image
{
    CGImageRef rawImageRef=image.CGImage;

    const float colorMasking[6] = {222, 255, 222, 255, 222, 255};

    UIGraphicsBeginImageContext(image.size);
    CGImageRef maskedImageRef=CGImageCreateWithMaskingColors(rawImageRef, colorMasking);
    {
        //if in iphone
        CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0.0, image.size.height);
        CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0); 
    }

    CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, image.size.width, image.size.height), maskedImageRef);
    UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
    CGImageRelease(maskedImageRef);
    UIGraphicsEndImageContext();    
    return result;
}

So simply pass your image to this method like so:

UIImage *newImage = [self changeWhiteColorTransparent: yourOldImage];