How Do I Get Audio Controls on Lock Screen/Control

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

func myplayer(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{}
}

Answer 2

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))

Answer 3

I Have this problem. You need only

audioSession.setCategory(.playback, mode: .default) or 
audioSession.setCategory(.playback, mode: .default, options: 
                                               .init(rawValue: 0)) 

Answer 4

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

Answer 5

There are already audio controls on the lock screen (the "remote control" interface). If you want them to control your app's audio, you need to make your app the remote control target, as described in Apple's documentation.