How can you play music from the iPod app while still receiving remote control events in your app?

Question

Ok, I\'m trying to let a user choose songs from their iPod library to listen to, but I still want to receive remote control notifications (headphones, lock screen osd, etc.)

Answer 1

HA! Solved! I knew it was possible! (Thanks Async-games.com support!)

Here's how to play iPod music in your app, with background support, and with your app receiving the remote control notifications.

You have to use AVPlayer (but not AVAudioPlayer. No idea why that is!) initialized with the asset URL from the MPMediaItem you got from the library picker (or current item in the MPMusicPlayerController or wherever), then set the audio session's category to Playable (do NOT enable the mixing override or you'll lose the remote events!) and add the appropriate keys to your info.plist file telling the OS your app wants to support background audio.

Done and done!

This lets you play items from your iPod library (except Audible.com files for some reason!) in the background and still get remote events. Granted since this is your audio player which is separate from, and will interrupt the iPod app, you have to do more work, but those are the breaks!

Damn though... I just wished it worked with Audible.com files. (For those interested, the reason it doesn't is the asset URL for an audible file returns nil. Stinks! But what can ya do!)

Answer 2

This is probably not going to be of any use anymore for the OP, but as it may be for people finding this page through googling, I will post it anyway.

An alternative (but rather ugly) approach, if you are only interested in the music remote control events and still want to be able to play the audible.com files...

Just keep using the MPMusicPlayer and track its notifications (now playing and state changed). To keep receiving these notifications in the background, you can do the "background thread magic" described in various places to keep your app from being suspended. You are not going to receive the remote controls directly (as the iPod player is receiving them), but by tracking the changes in "now playing" you can infer the ControlPreviousTrack and ControlNextTrack events, and by tracking the playbackState, you can infer the TogglePlayPause command.

The downside is that you are app is going to be running at all times for no good reason (although, to be fair, if iOS is programmed correctly, a background thread doing nothing should consume almost no battery).

Another alternative: use a MPMoviePlayer? I have checked that it works fine in the background, and should receive remote control events as well. It can play MPMediaItem natively, so hopefully the Audible.com files as well...

Answer 3

There is no way around this. If the users iPod app is playing an iPod selection, then all remote events are going to go to the iPod, not your app.

Answer 4

One think I noticed about MPMediaItemPropertyAssetURL is that, although the object returned is in NSURL but the absoluteString is something like this:

ipod-library://item/item.mp3?id=580807975475997900

Which is not what AVAudioPlayer want. What AVAudioPlayer want is NSURL object that is created from a file with a valid file path.

And I have no idea how to get file path from MPMediaItem. So I guess maybe AVPlayer is the way to go if you want to play iPod track without using MPMusicPlayer.