title: AVPlayerItemDidPlayToEndTime never reaches selector on Swift 3
body: <p>I'm adapting my app to Swift 3 and I'm encountering this problem. This used to work on Swift 2.2 but now it's broken. moviePlayBackFinished never gets called. I tried adding the observer in multiple ways, all without success.</p>
  
  <pre><code>    NotificationCenter.default.addObserver(self, selector: #selector(self.moviePlayBackFinished(_:)),
                                             name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem);
  
      NotificationCenter.default.addObserver(self, selector: #selector(moviePlayBackFinished(_:)),
                                             name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem);
  
      NotificationCenter.default.addObserver(self, selector: #selector(self.moviePlayBackFinished(sender:)),
                                             name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem);
  
  // (...)
  
  @objc func moviePlayBackFinished(sender : AnyObject) {
      print("playbackFinished");
      let zeroCM : CMTime = CMTime(seconds: 0, preferredTimescale: 1000000000);
      playerLayer.player?.seek(to: zeroCM);
  }
  
  @objc func moviePlayBackFinished(_ notification: Notification) {
      print("playbackFinished");
      let zeroCM : CMTime = CMTime(seconds: 0, preferredTimescale: 1000000000);
      playerLayer.player?.seek(to: zeroCM);
  }
  </code></pre>
  
  <p>Any ideas would be appriciated.</p>
  
  <p>Thank you</p>