title: how to route iPhone audio to the bluetooth headset
body: <p>I'm attempting to output audio to the bluetooth headset (not A2DP) using AVAudioPlayer, AVAudioSession and AudioSessionSetProperty.</p>
  
  <p>There seems to be functions to select the bluetooth headset as input (kAudioSessionProperty_OverrideCategoryEnableBluetoothInput), but no equivalent for setting the output.  This is done in the Voicemail app, where you can select the headset, handset speaker or speaker phone.   I've tried various combinations of SessionCategories and the AudioSession properties, but I just can't seem to hit on an approach that works.</p>
  
  <p>I'm sure someone has figured this out, care to share an example?</p>