title: how to create a pointy UIView
body: <p>I just saw local mind's app and they have a horizontal UIScrollView that has a selection with a pointy tip. How can I create such thing? I saw this often times in many apps where you don't just have a square frame, but you have a pointy edge to it, is this just a UIImage overlayed on top?</p>
  
  <p><img src="https://i.stack.imgur.com/W24Ly.png" alt="enter image description here"></p>
  
  <p>Other example would be <a href="http://forrst.com/posts/Npi/original" rel="nofollow noreferrer">this</a></p>