AVPlayer Audio Lock Screen updates stop working, only after another AVPlayer instance plays Video content - swift

Question

Summary:
If you only use AVPlayer to play streaming audio only in your application, then Lock Screen Updates will work just fine (many streams - one after another). However, if you use AVPlayer to play both Streaming Audio followed by a Local Video file (even while using separate instances of AVPlayer and on different view controllers), then when you try to play Streaming Audio again - nothing will show up on the Lock Screen any more. Not related to cleanup - because playing only multiple audio files in a row works fine and shows up on the Lock Screen every time, but as soon as you play 1 video file (Or even initialize it to any AVPlayer without calling .play() on it), audio Lock Screen updates permanently stop working, and you need to restart the app for it to work again. It sounds like an AVFoundation bug to me...
Detailed Breakdown:
I have an appliction with View Controllers A and B. View controller A is the presenter of view controller B (pushes it using a navigation controller). Both A and B have a seperate AVPlayer inside them (A's plays audio. B's plays video. Audio is streamed. Video is local file in docs directory).
VC A configures its AVPlayer to update the Lock Screen with the Artwork Image, progress status, forward 15s, back 15s buttons. Everything works great if only view controller A's player is used to play audio - no matter how many times I go back and forward to it (I.E. VC B's player is never used to play()). (The whole controller gets deinit correctly) The Lock Screen always works, and always updates all required playback information.
VC A (AVPlayer1) --> PUSH --> VC B (AVPlayer2)
This is the code to register for Lock Screen updates (including button and progress callbacks):
func setupNowPlaying() {
var nowPlayingInfo = [String : Any]()
nowPlayingInfo[MPMediaItemPropertyTitle] = title
nowPlayingInfo[MPMediaItemPropertyArtist] = artist
let artwork = MPMediaItemArtwork.init(boundsSize: self.artImage.size, requestHandler: { (size) -> UIImage in
return self.artImage
})
nowPlayingInfo[MPMediaItemPropertyArtwork] = artwork
guard let player = self.player else { return }
guard let currentItem = self.player?.currentItem else { return }
nowPlayingInfo[MPMediaItemPropertyPlaybackDuration] = currentItem.asset.duration.seconds
nowPlayingInfo[MPNowPlayingInfoPropertyPlaybackRate] = player.rate
nowPlayingInfo[MPNowPlayingInfoPropertyElapsedPlaybackTime] = currentItem.currentTime().seconds
let rcc = MPRemoteCommandCenter.shared()
let skipBackwardCommand = rcc.skipBackwardCommand
skipBackwardCommand.isEnabled = true
skipBackwardCommand.addTarget(handler: skipBackward)
skipBackwardCommand.preferredIntervals = [15]
let skipForwardCommand = rcc.skipForwardCommand
skipForwardCommand.isEnabled = true
skipForwardCommand.addTarget(handler: skipForward)
skipForwardCommand.preferredIntervals = [15]
UIApplication.shared.beginReceivingRemoteControlEvents()
MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
}
Additionally, the following is hooked up in AppDelegate (applicationWillResignActive), to enable background playback (standard stuff):
do {
try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [.mixWithOthers, .allowAirPlay, .allowBluetooth, .allowBluetoothA2DP ])
print("Playback OK")
try AVAudioSession.sharedInstance().setActive(true)
print("Session is Active")
} catch {
print(error)
}
The problem of Not showing anything on the lock screen starts to occur when VC B gets presented and plays video using its own separate AVPlayer. VC A's AVPlayer is first paused. If I call .play() on VC B's player then when I come back to VC A (by clicking Back < in the nav bar), the progress updates to the Lock Screen will never show up again (the whole playback UI doesn't show up), however the background playback still works.
So as soon as I use another AVPlayer on another View Controller, my original player will never be able to post updates to the Lock Screen UI, ever again, until the application is terminated and re-launched.
I tried to do full cleanup and re-init on the player in VC A.
I tried to just not call .play() on VC B. (Everything works fine with VC A in that case).
VC B's player is not registered for Lock Screen updates, because it just plays video in the app for preview purposes.
Something under-the-hood with Apple's AVPlayer breaks VC A's AVPlayer's Lock Screen updates capability, as soon as another instance of AVPlayer is introduced and used to play in another View Controller.
I know the issue is related to the second AVPlayer on the separate controller, because just not calling .play() on VC B's player, fixes the screen lock update disappearance issue on VC A's player.
How can I work around this? I don't want to remove VC A's player from superview, and pass it to VC B, and reconfigure it, then reconfigure it back again in VC A if the user comes back. (very laborious and error prone). It also currently bricks Lock Screen updates permanently, after the first time the user goes through VC B's playback (which is part of my happy path)
Thanks in advance,
Alex

Answer 1

I was able to avoid this problem by removing dependence on AVPlayerViewController in VC-B. Now I use a third party component called: "Player" (Cocoapods: "Player"), which uses an AVPlayerLayer, but not AVPlayerViewController. https://cocoapods.org/pods/Player
Unfortunately I lost my playback UI controls (progress bar, play button, full screen button - which AVPlayerViewController was giving me for free). So I will have to build some custom playback controls.
So it seems that AVPlayerViewController was causing the problem with the lock screen and breaking it. After switching to using "Player", which still uses AVPlayer, but not AVPlayerViewController, the problem went away, and I now always see my playback controls on the Lock Screen.