Question

I have an AVAudioPlayer that needs to continue in the background.

Audio is set as the background mode in the plist & this runs on launch:

[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[[RootController shared].view becomeFirstResponder];

AVAudioSession* session = [AVAudioSession sharedInstance];
[session setDelegate: self];
[session setActive:YES error:nil];
[session setCategory: AVAudioSessionCategoryPlayback error:nil];

- (BOOL)canBecomeFirstResponder { return YES; }

The Problem

Occasionally the AVAudioPlayer gets in this strange state where:

• It’s playing, but the play icon in the status bar disappears
• If I pause then play, the icon shows up for maybe a second, then disappears
• Here’s the kicker – if I call setCurrentTime while playing, the play icon shows & stays

I’ve sunk about 20 hours into this & would love any ideas.

Answer 1

Description of the Bug

If you are playing an AVAudioPlayer then you create an AVPlayer, the playing icon will disappear. Apparently AVPlayer immediately takes precedence & since it is not playing yet the play icon disappears from the status bar.

This causes some serious issues:

1. If the app is in the background, iOS will shut down your AVAudioPlayer within 5 seconds (because it doesn’t realize you’re playing audio)
2. The iOS remote shows a play button even though audio is playing
3. The play icon is not showing in the status bar

The Workaround

First off, if you don’t have to use AVPlayer, then don’t. I use it because I need to play a remote MP3 without downloading it first. I used to use this AudioStreamer class but gave up because it pops up an alert when the stream becomes disconnected along with a few other bugs that I couldn’t fix.

So if you’re stuck with AVPlayer, there’s only one way to re-connect playing status with your AVAudioPlayer. If you call setCurrentTime on the AVAudioPlayer then it will magically re-associate itself as the current player for the app. So you’ll need to call it after any AVPlayer is initialized and anytime you resume playback on your AVAudioPlayer.

I decided to subclass AVAudioPlayer so I could register it in a global list (when it is initialized) and unregister it when it is deallocated. I also overrode the play method so that any calls to resume playback would also call setCurrentTime. Then I subclassed AVPlayer so that any time one is initialized, all active AVAudioPlayers call setCurrentTime on themselves. Last thing – you’ll have to call setCurrentTime after a short, maybe 1 second, delay or else it will have no effect.

No kidding, this is the result of nearly 40 hours of troubleshooting.