title: MPNowPlayingInfoCenter info being overwritten by AVPlayer
body: <p>I'm working an iOS application that uses an AVPlayer to play songs represented by AVPlayerItems. </p>
  
  <p>I've tried setting the nowPlayingInfo property of MPNowPlayingInfoCenter.defaultCenter() but it appears that the info gets immediately overwritten by the AVPlayer since it needs to update other info like elapsedTime and playbackDuration. </p>
  
  <p>Even immediately after the program executes</p>
  
  <pre><code>MPNowPlayingInfoCenter.defaultCenter().nowPlayingInfo?[MPMediaItemPropertyTitle] = "Title"
  </code></pre>
  
  <p>The printout of <code>MPNowPlayingInfoCenter.defaultCenter().nowPlayingInfo</code> is</p>
  
  <blockquote>
    <p>Info: ["MPNowPlayingInfoPropertyElapsedPlaybackTime": 34.89555007300078, "AVNowPlayingInfoControllerIdentifierKey": &lt;__NSConcreteUUID 0x13778e9b0> 9141DD1C-FD09-4210-B3C7-B948522E3AF6, "playbackDuration": 198.2516666666667, "MPNowPlayingInfoPropertyPlaybackRate": 1]</p>
  </blockquote>
  
  <p>What am I doing wrong? Is it possible to store additional metadata like title/album name in an AVPlayerItem so it gets displayed on the info center? </p>
  
  <p>Also, what is AVNowPlayingInfoControllerIdentifierKey? There do not seem to be any classes named AVNowPlayingInfoController. </p>