How Do I Get Audio Controls on Lock Screen/Control Center from AVAudioPlayer in Swift

Question

New to iOS development, so here goes. I have an app that is playing audio - I'm using AVAudioPlayer to load single files by name in the app's assets. I don't want to query the user's library, only the files provided. Works great, but, I want the user to be able to pause and adjust volume from the lock screen.

func initAudioPlayer(file:String, type:String){
    let path = NSBundle.mainBundle().pathForResource(file, ofType: type)!
    let url = NSURL(fileURLWithPath: path)
    let audioShouldPlay = audioPlaying()
    do{
        try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
        try AVAudioSession.sharedInstance().setActive(true)
        let audioPlayer:AVAudioPlayer = try AVAudioPlayer(contentsOfURL: url)
        audioPlayer.volume = slider.value
        audioPlayer.numberOfLoops = -1
        audioPlayer.prepareToPlay()
        if(audioShouldPlay){
            audioPlayer.play()
//                let mpic = MPNowPlayingInfoCenter.defaultCenter()
//                mpic.nowPlayingInfo = [MPMediaItemPropertyTitle:"title", MPMediaItemPropertyArtist:"artist"]
        }
    }
    catch{}
}

My use of AVAudioSession and MPNowPlayingInfoCenter were just experiments from reading other related posts.

Background mode is enabled for audio in my app's plist file

Answer 1

You need to invoke beginReceivingRemoteControlEvents() otherwise it will not work on the actual device.

Swift 3.1

UIApplication.shared.beginReceivingRemoteControlEvents()

If you would like to specify custom actions for the MPRemoteCommandCenter:

let commandCenter = MPRemoteCommandCenter.shared()
commandCenter.nextTrackCommand.isEnabled = true
commandCenter.nextTrackCommand.addTarget(self, action:#selector(nextTrackCommandSelector))

---

edit/update:

Apple has a sample project showing how to Becoming a Now Playable App

Answer 2

To implement this functionality, use the Media Player framework’s MPRemoteCommandCenter and MPNowPlayingInfoCenter classes with AVPlayer.

import MediaPlayer
import AVFoundation

// Configure AVPlayer
var player = AVPlayer()

Configure the Remote Command Handlers

Defines a variety of commands in the form of MPRemoteCommand objects to which you can attach custom event handlers to control playback in your app.

    func setupRemoteTransportControls() {
    // Get the shared MPRemoteCommandCenter
    let commandCenter = MPRemoteCommandCenter.shared()

    // Add handler for Play Command
    commandCenter.playCommand.addTarget { [unowned self] event in
        if self.player.rate == 0.0 {
            self.player.play()
            return .success
        }
        return .commandFailed
    }

    // Add handler for Pause Command
    commandCenter.pauseCommand.addTarget { [unowned self] event in
        if self.player.rate == 1.0 {
            self.player.pause()
            return .success
        }
        return .commandFailed
    }
}

Provide Display Metadata

Provide a dictionary of metadata using the keys defined by MPMediaItem and MPNowPlayingInfoCenter and set that dictionary on the default instance of MPNowPlayingInfoCenter.

func setupNowPlaying() {
    // Define Now Playing Info
    var nowPlayingInfo = [String : Any]()
    nowPlayingInfo[MPMediaItemPropertyTitle] = "My Movie"

    if let image = UIImage(named: "lockscreen") {
        nowPlayingInfo[MPMediaItemPropertyArtwork] =
            MPMediaItemArtwork(boundsSize: image.size) { size in
                return image
        }
    }
    nowPlayingInfo[MPNowPlayingInfoPropertyElapsedPlaybackTime] = playerItem.currentTime().seconds
    nowPlayingInfo[MPMediaItemPropertyPlaybackDuration] = playerItem.asset.duration.seconds
    nowPlayingInfo[MPNowPlayingInfoPropertyPlaybackRate] = player.rate

    // Set the metadata
    MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
}

For more information refer Apples official Documentation