title: iOS: How to add an Alpha Channel to a native iPhone Picture
body: <p>I'm trying to mask a picture taken with my iphone.
  <a href="https://stackoverflow.com/questions/9872975/how-to-mask-an-image-in-ios-sdk">Here</a> I found a way how to do that. However, the image-to-be-masked apparently needs an alpha channel, and pictures from the iPhone don't have that.
  So, I found <a href="https://stackoverflow.com/questions/5111671/iphone-uiimage-mask-and-copyimageandaddalphachannel-function">this</a> topic discussing how to add such a channel. Unfortunately, that code doesn't work for me (Xcode 6, iOS 7/8)</p>
  
  <p>Does any of you know how to accomplish this?</p>
  
  <p>Thanks in advance</p>