title: Display UIView with a UILabel text mask
body: <p>I'm trying to add a <code>UIView</code> to a <code>UILabel</code>, so that the text is the view's mask, enabling me to do things like animated text backgrounds (much like the slide to unlock label on the lockscreen).</p>
  
  <p>The way I was planning on doing it was using the <code>mask</code> property on the view's <code>layer</code> to mask it to the shape of the text. However, I cannot find a way to get the <code>UILabel</code>'s text shape as a <code>CALayer</code>.</p>
  
  <p>Is this even possible? I can only find solutions that override the <code>-(void)drawRect:</code> method in the <code>UILabel</code>, but this wouldn't give me much flexibility.</p>