title: iOS: How do I detect if music is playing in any background music app?
body: <p>I currently have my game correctly handling disabling its own BGM when music is playing in the built-in iPod app, but it does not detect when an app such as Pandora is playing music.</p>
  
  <p>Currently, in my <code>applicationDidBecomeActive</code> method, I check <code>[[MPMusicPlayerController iPodMusicPlayer] playbackState]</code> to determine whether music is playing. What is the equivalent of this to check if an app like Pandora is playing audio in the background?</p>