MPMusicPlayerController: too many notifications

Question

i'm using notifications from the NSNotificationCenter to pick up MPMusicPlayerController notifications.

I use these notifications to change the state of a button in my view from "play" to "pause" states.

It "works" however sometimes the MPMusicPlayerController (iPodMusicPlayer to be exact) does not report the correct state and thus my buttons get all messed up, and don't operate correctly.

Having done some investigating, I found that notifications are triggered a lot when changing the current playing song.

For example: When I choose a song, I call: - stop - setQueueWIthItemCOllection - nowPlayingItem - play

These calls, launch so many notifications. After the stop, I get notified 2 times for nowPlayingItem for example after the nowPlayingItem call... ???

Also, after even forcing my buttons to behave relative to their "picture" state rather than the MPMusicPlayerController playbackstate, the controller still does not reflect the correct state. For example, a song will be playing in the background (I can hear it, the "play" icon is on in the far top right of the ipad next to the battery icon), but the MPMusicPlayerController iPodMusicPlayer reports state "Pause" ...

Does anyone have any info or help on this ?

Cheers

After many long debug sessions, I decided to "quit". Reverted to AVPlayer instead of the MPMusicPlayerController ... Subject can be closed... — teuteuguy
Well, I didn't quit (yet), but there are definitely some Notifications being send out multiple times and in the wrong order... — Klaas
Did you have iTunes Match activated on your device? Then it could be the reason that the songs first hat to be downloaded. — Klaas
No I did not have iTunes Match. I was sending a Collection into the player via the enqueue command. Then i'd set the playingitem in order to start playing from the desired item in the Collection. If I recall correctly, this would trigger a state change => playing ... (and it wasn't playing at all). Then finally I'd activate the play function, and it would start playing. Triggering yet again another state change => Playing. Problem is that I would use the state to define the look of the play/pause button. Sometimes the player would get stuck in a state of "play" and signal "paused" ... — teuteuguy

inzan inzan · Accepted Answer · 2012-08-15T07:56:01

I believe I had this same issue and found that I had to do two things to fix it:

1) Copy the incoming MPMediaItemCollection's items array and create a new MPMediaItemCollection with it

2) Either set the nowPlayingItem or the currentPlaybackTime on the player (or both)

Once I did these two things, the notifications I received from the music player were generated the expected number of times and they all had playbackStates that were accurate (reflecting the actual state of the player).

Hope this is helpful...

-(void)setUserMediaItemCollection:(MPMediaItemCollection *)newUserMediaItemCollection
{
    [userMediaItemCollection release];

    //I FOUND YOU MUST COPY THE INCOMING ITEMS TO A NEW COLLECTION
    NSArray *combinedMediaItems = [newUserMediaItemCollection.items copy];
    userMediaItemCollection     = [[MPMediaItemCollection collectionWithItems: (NSArray *) combinedMediaItems] retain];
    [combinedMediaItems release];
    [self.musicPlayer setQueueWithItemCollection:userMediaItemCollection];
    //


    //ALSO FOUND YOU MUST SET EITHER THE NOWPLAYING ITEM OR STARTTIME OR PLAYBACK STATE CAN BE WRONG
    if ([[userMediaItemCollection items] count])
    {
        //MPMediaItem *nowPlayingItem   = [[userMediaItemCollection items] objectAtIndex:0];
        //[self.musicPlayer setNowPlayingItem:nowPlayingItem];
        NSTimeInterval startTime    = 0.0;
        musicPlayer.currentPlaybackTime = startTime;
    }
    //
}

MPMusicPlayerController: too many notifications

1 Answers