title: Update song/track info from iPhone app
body: <p>I have an app that implements the MediaPlayer framework. I can read the state, stop, play, skip, reverse, etc.</p>
  
  <p>How can I update the BPM, or the comments, etc...</p>
  
  <p>I have tried a direct assignment on <code>MPMediaItemPropertyBeatsPerMinute</code> and I get the error:</p>
  
  <blockquote>
    <p>Read-only variable is not assignable</p>
  </blockquote>
  
  <p>I currently have a <code>UITextField</code> for collecting user input, and a <code>UIButton</code> to save the data.</p>
  
  <p>What methods can be implemented to save/push the data in the <code>UITextField</code> to the tracks MetaData. </p>
  
  <p>Any leads would be great!</p>