How to mask a UIView

Question

I'm working on an app where I draw a UIView via code and I fill it with a UIColor. Next thing I want to load a mask.png file (no transparency, just black and white) and mask the UIView to change its visual appearance.

Any idea how to do this?

Answer 1

// Create your mask layer CALayer* maskLayer = [CALayer layer]; maskLayer.frame = CGRectMake(0,0,yourMaskWidth ,yourMaskHeight); maskLayer.contents = (__bridge id)[[UIImage imageNamed:@"yourMaskImage.png"] CGImage];  // Apply the mask to your uiview layer         yourUIView.layer.mask = maskLayer; 

Remember to import QuartzCore and add the framework

#import <QuartzCore/QuartzCore.h> 

It is very easy but I didn't find the answer anywhere!

Answer 2

iOS 8 introduces the maskView property which allows you to use an alternate view to provide the mask image. In Swift:

if let maskImage = UIImage(named: "MaskImage") {     myView.maskView = UIImageView(image: maskImage) } 

Note that you need to supply an image which actually has transparency; an image with white parts (for opaque) and black parts (for transparent) won't work.