Xcode swift - Background mode - Audio in AVPlayer when locked

Question

I have got an AVPlayer setup but I cant seem to get the video audio to continue to play when the phone is locked or on the home screen. I have edited the info.plist and enabled the audio background mode but I think need to add some code. Please could you help me out. Thanks

Here is my code:

import UIKit
import AVFoundation
import AVKit

class ViewController: UIViewController {

    @IBAction func WarmUp(sender: UIButton)
    {
        WarmUpVideo()
    }

    func WarmUpVideo()
    {
        let filePath = NSBundle.mainBundle().pathForResource("132", ofType: "MOV")
        let videoURL = NSURL(fileURLWithPath: filePath!)

        let player = AVPlayer(URL: videoURL)
        let playerViewController = AVPlayerViewController()

        playerViewController.player = player

        self.presentViewController(playerViewController, animated: true) { () -> Void in playerViewController.player!.play()
        }

    }

    func playExternalVideo()
    {

}


    @IBAction func CoolDown(sender: UIButton)
    {
        CoolDownVideo()
    }

    func CoolDownVideo()
    {
        let filePath = NSBundle.mainBundle().pathForResource("132", ofType: "mp4")
        let videoURL = NSURL(fileURLWithPath: filePath!)

        let player = AVPlayer(URL: videoURL)
        let playerViewController = AVPlayerViewController()

        playerViewController.player = player

        self.presentViewController(playerViewController, animated: true) { () -> Void in playerViewController.player!.play()
        }

    }

}

Answer 1

I think you're missing the following code:

do {
    try AVAudioSession.sharedInstance()
                          .setCategory(AVAudioSession.Category.playback)
    print("AVAudioSession Category Playback OK")
    do {
        try AVAudioSession.sharedInstance().setActive(true)
        print("AVAudioSession is Active")
    } catch let error as NSError {
        print(error.localizedDescription)
    }
} catch let error as NSError {
    print(error.localizedDescription)
}

Add this to your viewDidLoad.

Typical 2019 syntax of the key line of code:

try AVAudioSession.sharedInstance().setCategory(.playback)

In some cases you may want:

try AVAudioSession.sharedInstance().setCategory(.playback, options: .mixWithOthers)

---

You MUST add this ONE item in plist (one item only, beware of old examples);

<key>UIBackgroundModes</key>
<array>
    <string>audio</string>
</array>

Which is:

NOTE: years ago you had to also add UIApplicationExitsOnSuspend - DO NOT add this today.

Answer 2

I found the solution on Apple's Documentation. Additionally to the background modes, you need to set to nil the player in order to avoid auto pause.

Here's the link:

https://developer.apple.com/documentation/avfoundation/media_assets_playback_and_editing/creating_a_basic_video_player_ios_and_tvos/playing_audio_from_a_video_asset_in_the_background