title: Masking an image view with an image view
body: <p>I am struggling to figure out how I can mask one image view to another. I am attempting to mask a chat bubble image view to a image view that contains a picture, exactly like iMessage.</p>
  
  <p>I have tried every combination of imageView.layer.mask I can possibly think of and it all fails. The hard part of this is because the bubble image view is made from a stretchable image. I cannot use a regular image mask it doesn't work.</p>
  
  <p>Any ideas??</p>