4.3 finally :) I am searching right now how to add air play button to custom view. I have MPMoviePlayer that load movie. I disabled standard controls and added overlay view
If you want just the AirPlay button without the volume slider follow the instructions in Jilouc's answer and then set the following properties on the myVolumeView:
[myVolumeView setShowsVolumeSlider:NO];
[myVolumeView setShowsRouteButton:YES];
That will hide the volume slider but keep the route button.