title: Detecting active AVAudioSessions on iOS device
body: <p>I'm trying to figure out if this is possible - my app activates an audio session that is initialized as:</p>
  
  <pre><code>[[[AVAudioSession alloc] init] setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionMixWithOthers error:&amp;error];
  </code></pre>
  
  <p>I would like to be able to understand when an additional audio session that originated from another app or the OS is playing.</p>
  
  <p>I know about the ability to implement the delegate methods <code>beginInterruption:</code> and <code>endInterruption</code> but these won't get invoked because of the <code>AVAudioSessionCategoryOptionMixWithOthers</code> option I'm using.</p>
  
  <p>Is there a way to achieve this without using private API?</p>
  
  <p>Thanks in advance.</p>