title: Play a song specified by a user after a UILocalNotification fires
body: <p>What I'm trying to achieve here is simple to describe but hard to achieve:</p>
  
  <p>Given that the user has created a UILocalNotification, how can I allow them to specify a song from their own iPhone that will play after the notification fires?</p>
  
  <p>I would like the user to be able to select a song from their own music list.</p>
  
  <p>Furthermore, how do I ensure that the song plays even if the device is locked and the ring volume is turned off?</p>