Question

The last two lines of code below it’s returning gives me a potential memory leak warning. …..Is this a true positive warning or false positive warning? If true, how do i fix it? Thanks a lot for your help!

-(UIImage*)setMenuImage:(UIImage*)inImage isColor:(Boolean)bColor
{ 
    int w = inImage.size.width + (_borderDeep * 2);
    int h = inImage.size.height + (_borderDeep * 2);

    CGColorSpaceRef colorSpace;
    CGContextRef context;

    if (YES == bColor)
    {
        colorSpace = CGColorSpaceCreateDeviceRGB();
        context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
    }
    else
    {
        colorSpace = CGColorSpaceCreateDeviceGray();
        context = CGBitmapContextCreate(NULL, w, h, 8, w, colorSpace, kCGImageAlphaNone);        
    }

    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);

    CGContextDrawImage(context, CGRectMake(_borderDeep, _borderDeep, inImage.size.width, inImage.size.height), inImage.CGImage);

    CGImageRef image = CGBitmapContextCreateImage(context);
    CGContextRelease(context); //releasing context
    CGColorSpaceRelease(colorSpace); //releasing colorSpace

    //// The two lines of code above caused Analyzer gives me a warning of potential leak.....Is this a true positive warning or false positive warning? If true, how do i fix it?
    return [UIImage imageWithCGImage:image];
}

Answer 1

You’re leaking the CGImage object (that’s stored in your image variable). You can fix this by releasing the image after creating the UIImage.

UIImage *uiImage = [UIImage imageWithCGImage:image];
CGImageRelease(image);
return uiImage;

The reason for this is that CoreGraphics follows the CoreFoundation ownership rules; in this case, the “Create” rule. Namely, functions with “Create” (or “Copy”) return an object that you are required to release yourself. So in this case, CGBitmapContextCreateImage() is returning a CGImageRef that you are responsible for releasing.

---

Incidentally, why aren’t you using the UIGraphics convenience functions to create your context? Those will handle putting the right scale on the resulting UIImage. If you want to match your input image, you can do that as well

CGSize size = inImage.size;
size.width += _borderDeep*2;
size.height += _borderDeep*2;
UIGraphicsBeginImageContextWithOptions(size, NO, inImage.scale); // could pass YES for opaque if you know it will be
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
[inImage drawInRect:(CGRect){{_borderDeep, _borderDeep}, inImage.size}];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;