Playing audio in background - iphone

Question

I am showing media hierarchy in the table view. When I tap on a song in the table view, it plays the song using MPMoviePlayerViewController. But when I click on the done button, the sound stops playing . I have created the following code:
NSURL *songUrl=[operationControl getSong:stringId];
mediaPlayerController = [[MPMoviePlayerViewController alloc] initWithContentURL:songUrl];
[self presentModalViewController:mediaPlayerController animated:YES];
[[mediaPlayerController moviePlayer] play];
I to want to browse the media hierarchy as well as play the song in the background. How can I achieve this?

Answer 1

You should start AVAudioSession and declare in main plist that your application plays music in background.
in didFinishLaunchingWithOptions:
// Setup audio session
AVAudioSession *sharedSession = [AVAudioSession sharedInstance];
[sharedSession setCategory:AVAudioSessionCategoryPlayback error:nil];
in applicationDidBecomeActive:
[sharedSession setActive:YES error:nil]; // FIXME: Error handling
In main plist add: Required background modes - App plays audio

Answer 2

It sounds like you didn't set up your Audio Session correctly. From
http://developer.apple.com/iphone/library/documentation/AudioVideo/Conceptual/MultimediaPG/UsingAudio/UsingAudio.html
For example, when using the default audio session, audio in your application stops when the Auto-Lock period times out and the screen locks. If you want to ensure that playback continues with the screen locked, include the following lines in your application’s initialization code:
NSError *setCategoryErr = nil;
NSError *activationErr = nil;
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error:&setCategoryErr];
[[AVAudioSession sharedInstance] setActive:YES error:&activationErr];
The AVAudioSessionCategoryPlayback category ensures that playback continues when the screen locks. Activating the audio session puts the specified category into effect.