title: Using circular progress bar with masked image?
body: <p>I am working on a circular progress bar for custom game center achievements view and I have kind of "hit the wall". I am struggling with this for over two hours and still cannot get it to work.</p>
  
  <p>The thing is, that I need a circular progress bar, where I would be able to set (at least) the track(fill) image. Because my progress fill is a rainbow like gradient and I am not able to achieve the same results using only code.</p>
  
  <p>I was messing with CALayers, and drawRect method, however I wasn't successful. Could you please give me a little guidance?</p>
  
  <p>Here are examples of the circular progress bars: 
  <a href="https://github.com/donnellyk/KDGoalBar">https://github.com/donnellyk/KDGoalBar</a>
  <a href="https://github.com/danielamitay/DACircularProgress">https://github.com/danielamitay/DACircularProgress</a></p>
  
  <p>I just need the fill to be an masked image, depending on the progress. If you could even make it work that the progress would be animated, that would be really cool, but I don't require help with that :)</p>
  
  <p>Thanks, Nick</p>