I have an app that streams video from the net and plays it using an MPMoviePlayerController object for playback on the device or via AirPlay.
The app supports background operation and has the 'audio' option listed within the required UIBackgroundModes key in its plist file.
When playing over AirPlay, the app can successfully be pushed to the background and the video continues to play properly. So far, so good.
According to the Apple documentation:
Including the audio key tells the system frameworks that they should continue playing and make the necessary callbacks to the app at appropriate intervals. If the app does not include this key, any audio being played by the app stops when the app moves to the background.
However, these callbacks are not being made.
The app uses two types of callback: those associated with notifications MPMoviePlayerController and AVPlayer send during playback together with timer based callbacks that monitor the playback position and performance stats for monitoring purposes.
Looking at Apple's notes, I would certainly expect to receive the first type of callback so that the app can respond to MPMoviePlayerPlaybackStateDidChangeNotification, MPMoviePlayerPlaybackDidFinishNotification and MPMoviePlayerLoadStateDidChangeNotification, but this doesn't happen.
Does anyone know if it is possible to receive these during background AirPlay playback and, if so, how was this achieved?
**Please note: the app works correctly when running in the foreground and receives the notifications fine. It is only when pushed to the background and playing over AirPlay that the notifications are not received.
Likewise, the video plays over AirPlay in the background properly. It is only the notifications which are not received**
For completeness, I ought to add that at present I believe there is no solution to this problem.
I've discussed it directly with Apple via tech support and there was no practical work-around available.
This functionality was needed to allow the app to record stats about the playback of the stream at regular intervals. While this is fine when the video is played on the device's screen and over AirPlay while the app is in the foreground, it isn't possible to do with the app in the background.
The solution I've gone with instead is to disable the idle timer during all types of playback and to re-enable afterwards using:
[UIApplication sharedApplication].idleTimerDisabled = YES;
and
[UIApplication sharedApplication].idleTimerDisabled = NO;
While this isn't a solution to the original question, it's a workaround for avoiding the issue in the first place.