xcode - MPNowPlayingInfoCenter info is not displayed on iOS 8

Question

I'm developing a music application, which should play music in the background.

I use the MPMoviePlayerController to play the music. My code to initiate the MPMoviePlayerController:

NSString* resourcePath = [[NSBundle mainBundle] resourcePath];
resourcePath = [resourcePath stringByAppendingString:@"/music.m4a"];
NSError* err;
self.player = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL fileURLWithPath:resourcePath]];
if (err) {
    NSLog(@"ERROR: %@", err.localizedDescription);
}
AVAudioSession *session = [AVAudioSession sharedInstance];
[session setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionMixWithOthers error:nil];
[session setActive:YES error:nil];
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self.player setShouldAutoplay:NO];
[self.player setControlStyle: MPMovieControlStyleEmbedded];
self.player.view.hidden = YES;
[self.player prepareToPlay];

When I execute [self.player play]; the music starts. But I also want to display the name of the song, the name of the album and the album artwork in the LockScreen and the ControlCenter. I'm using the following code:

Class playingInfoCenter = NSClassFromString(@"MPNowPlayingInfoCenter");
    if (playingInfoCenter) {
        NSMutableDictionary *songInfo = [[NSMutableDictionary alloc] init];
        MPMediaItemArtwork *albumArt = [[MPMediaItemArtwork alloc] initWithImage: [UIImage imageNamed:@"artwork.png"]];
        [songInfo setObject:@"SongName" forKey:MPMediaItemPropertyTitle];
        [songInfo setObject:@"ArtistName" forKey:MPMediaItemPropertyArtist];
        [songInfo setObject:@"AlbumTitle" forKey:MPMediaItemPropertyAlbumTitle];
        [songInfo setObject:albumArt forKey:MPMediaItemPropertyArtwork];
        [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:songInfo];
    }

But nothing gets displayed in the LockScreen. It doesn't get displayed in the ControlCenter either.

How can I solve my problem? I didn't find anything on the internet.

Thanks in advance, Fabian.

Aiken

Is your code actually being executed? – Addict

Yes, [[MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo objectForKey:MPMediaItemPropertyTitle] returns the right SongName. – Aiken

Aha! That's really great news. So not only is your code running, but it is actually setting the nowPlayingInfo successfully. So let me ask you this - are you first responder, so that you are successfully receiving the remote control events from the lock screen and control center? – Addict

The remote controls are actually not displayed in the lock screen and I don't think, my app becomes the first responder. – Aiken

I think that's the problem, then. You can't influence the lock screen unless you are first responder. – Addict

Okay, and how I can solve the problem? – Aiken

You have to be first responder. And there are other requirements as well. See my answer below, along with the linked material. – Addict

Answer 1

The problem is that you are not satisfying the requirements to become master of the lock screen and control center, as I explain in my book. You should be seeing the modern (iOS 8) equivalent of this:

The fact that you are not seeing it suggests that you are omitting one or more of the requirements, which I list (quoting directly from my book here):

• Your app must contain a UIResponder in its responder chain that returns YES from canBecomeFirstResponder, and that responder must actually be first responder.
• Some UIResponder in the responder chain, at or above the first responder, must implement remoteControlReceivedWithEvent:.
• Your app must call the UIApplication instance method beginReceivingRemoteControlEvents.
• Your app’s audio session’s policy must be Playback.
• Your app must be emitting some sound.

I don't know which of those you are omitting; it could be more than one. You might like to compare your code with a working example, here:

https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/iOS7bookExamples/bk2ch14p653backgroundPlayerAndInterrupter/backgroundPlayer/backgroundPlayer/ViewController.m

Addict

You're very welcome. It's a lot of requirements! Omitting one of them is easy, and then things mysteriously don't work. :( – Addict

Any luck getting this to work when playing through a WKWebView? I can get other sources to change the now playing, just not when playing through a WKWebView. – Mog

Is this possible in AVQueuePlayer?means can i add NSMutableDictionary externally in AVplayer for set the artwork ..etc – Burnet

@Addict that post was really helpful for me and solved my problem, thanks! – Gladstone

I verified that my app does do everything in the list, but the lock screen controls and information do not appear when I start the app and play the stream the first time. I have to stop and restart the stream (Icecast) and then on the second attempt the lock screen controls and information appear. The steps on the first attempt and second attempt are exactly the same (i.e. no threading or asynchronous race conditions). So I have no idea why the lock screen is not working correctly on the first attempt. – Bellamy

Answer 2

Want to expand @matt's answer - setting nowPlayingInfo is useless when you use AVAudioSessionCategoryOptionMixWithOthers option.

Ute

Came here to add this - if you add .mixWithOthers key you won't be able to set the control center details as you might expect. – Polygamous

Answer 3

Expanding further on @matt's answer, it's required that you call endReceivingRemoteControlEvents and resignFirstResponder when the app comes back into the foreground (applicationDidBecomeActive). Otherwise the OS assumes you are a bad actor (or forgot to turn them off) and turns off your ability to show the sleep controls entirely, even after you call beginReceivingRemoteControlEvents again. I added these calls and now the Sleep Controls always show when they should.

Debose

Answer 4

Want to explain @zakhej's answer - what's happens when set AVAudioSessionCategoryOptionMixWithOthers.

1. MPNowPlayingInfoCenter is a singleton, which means can only one application set it.
2. AVAudioSession is shared with other apps, every app can set it.

so. when you set category AVAudioSessionCategoryAmbient, AVAudioSessionCategoryPlayAndRecord and mix with others, AVAudioSessionCategoryPlayback and mix with others, setting MPNowPlayingInfoCenter's nowPlayingInfo is useless.

Tranship