iOS 13.4 accessing MPMusicPlayerController.systemMusicPlayer crashes the app

Question

I have a player control in the app the controls system music player (Prev Play/Pause Next).

To show proper Play/Pause state I'm adding an observer to MPMusicPlayerControllerPlaybackStateDidChange notification.

Everything goes smooth while Apple Music App is running. But if I close the Apple Music app and press play button in my app that triggers the playPause() function the app gets crashed right after I tried to get current playbackState while handling new MPMusicPlayerControllerPlaybackStateDidChange notification.

func playPause() {
    let isPlaying = MPMusicPlayerController.systemMusicPlayer.playbackState == .playing
    isPlaying ? controller.pause() : controller.play()
}

The code that handles that notification:

@objc
private func onPlayBackStateChanged() {

    let playbackState = MPMusicPlayerController.systemMusicPlayer.playbackState // <<< This line crashes the app
    updatePlaybackState(playbackState)
}

Right before crash I'm receiving this log:

2020-03-25 13:46:20.471063+0200 MYAPP[405:14911] [SDKPlayback] prepareToPlay failed [no target descriptor]
2020-03-25 13:46:33.305925+0200 MYAPP[405:14911] [SDKPlayback] prepareToPlay failed [no target descriptor]
2020-03-25 13:46:41.498197+0200 MYAPP[405:15072] [SDKPlayback] systemMusicPlayer connection invalidated

This code works well with iOS <13.3x but it doesn't work with iOS 13.4. Is this new bug from Apple or am I doing something wrong? How to fix this bug?

Answer 1

I'm having the exact same issue - feature worked fine in iOS 13.3 but broke in 13.4. I filed a bug with Apple through Feedback Assistant. They were able to recreate the issue and there is a fix in iOS 13.5 beta 4 (the fix worked for me).

Should be fixed in the release version of 13.5.