title: Player swift crash app
body: <p>I have add Player-swift in my project to play video but when i pop that controller app getting crash with following log</p>
  
  <blockquote>
    <p>Terminating app due to uncaught exception 'NSRangeException', reason:
    'Cannot remove an observer  for the key
    path "rate" from  because it is not
    registered as an observer.'</p>
  </blockquote>
  
  <p>any one have any idea? i have used this player <a href="https://github.com/piemonte/Player" rel="nofollow noreferrer">https://github.com/piemonte/Player</a></p>
  
  <p>Thanks in advance !</p>