How do I get my AVPlayer to play while app is in background?

Question

I've done my homework... been reading here, the docs, googling, stackoverflowing... but still no luck in making my sound stick when the user makes the app go into the background.

What I have done so far: Added the UIBackgroundModes, audio to the plist-file.

First this code:

radioAudio = [[AVAudioSession alloc] init];
[radioAudio setCategory:AVAudioSessionCategoryPlayback error:nil];
[radioAudio setActive:YES error:nil];

Then this:

NSString *radioURL = @"http://xxx.xxx.xxx/radio.m3u";
radioPlayer = [[AVPlayer playerWithURL:[NSURL URLWithString:radioURL]] retain];

But as soon as the user hits the home-button, my sound dies.

I also found this, but not added yet cuase some stuff I've read says it is not needed;

newTaskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:NULL];
     if (newTaskId != UIBackgroundTaskInvalid && bgTaskId != UIBackgroundTaskInvalid)
        [[UIApplication sharedApplication] endBackgroundTask: bgTaskId];
bgTaskId = newTaskId;

Right now I have no idea where I should go to make my AVPlayer let the radio sing while the user does other stuff on the phone. I am testing this on an iPhone 4 with 4.2. Building it for 4.0.

Anyone have any suggestions what I should do?

Answer 1

UPDATE IOS 11.2 with Swift 4:

Now if you are using AVPlayer to play music files you should also configure MPNowPlayingInfoCenter.default() to show now playing info on the lock screen.

Below code will show now playing controls on the screen but it won't be able to respond any commands.

If you also want to controls to work you should check apple's sample project here: https://developer.apple.com/library/content/samplecode/MPRemoteCommandSample/Introduction/Intro.html#//apple_ref/doc/uid/TP40017322

Apple sample code covers all but i find it confusing.

If you want to play sound and show controls on the lock screen these steps will do just fine.

IMPORTANT NOTE: If you are NOT using AVPlayer to play sound. If you are using some third party libraries to generate sound or playback a sound file you should read comments inside the code. Also if you are using ios simulator 11.2 you won't be able to see any controls on lock screen. You should use a device to see it work.

---

1- Select project -> capabilites -> set background modes ON -> tick Audio, AirPlay and Picture in Picture

2- AppDelegate.swift file should look like this :

import UIKit

import AVFoundation

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate
{

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool
    {
        // Override point for customization after application launch.

        do
        {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().setActive(true)

         //!! IMPORTANT !!
         /*
         If you're using 3rd party libraries to play sound or generate sound you should
         set sample rate manually here.
         Otherwise you wont be able to hear any sound when you lock screen
         */
            //try AVAudioSession.sharedInstance().setPreferredSampleRate(4096)
        }
        catch
        {
            print(error)
        }
        // This will enable to show nowplaying controls on lock screen
        application.beginReceivingRemoteControlEvents()

        return true
    }
}

3- ViewController.swift should look like this:

import UIKit

import AVFoundation
import MediaPlayer

class ViewController: UIViewController
{

    var player : AVPlayer = AVPlayer()

    override func viewDidLoad()
    {
        super.viewDidLoad()


        let path = Bundle.main.path(forResource: "music", ofType: "mp3")
        let url = URL(fileURLWithPath: path!)

        // !! IMPORTANT !!
        /*
            If you are using 3rd party libraries to play sound 
            or generate sound you should always setNowPlayingInfo 
            before you create your player object.

            right:
            self.setNowPlayingInfo()
            let notAVPlayer = SomePlayer()

            wrong(You won't be able to see any controls on lock screen.):
            let notAVPlayer = SomePlayer()
            self.setNowPlayingInfo()
         */

        self.setNowPlayingInfo()
        self.player = AVPlayer(url: url)

    }


    func setNowPlayingInfo()
    {
        let nowPlayingInfoCenter = MPNowPlayingInfoCenter.default()
        var nowPlayingInfo = nowPlayingInfoCenter.nowPlayingInfo ?? [String: Any]()

        let title = "title"
        let album = "album"
        let artworkData = Data()
        let image = UIImage(data: artworkData) ?? UIImage()
        let artwork = MPMediaItemArtwork(boundsSize: image.size, requestHandler: {  (_) -> UIImage in
            return image
        })

        nowPlayingInfo[MPMediaItemPropertyTitle] = title
        nowPlayingInfo[MPMediaItemPropertyAlbumTitle] = album
        nowPlayingInfo[MPMediaItemPropertyArtwork] = artwork

        nowPlayingInfoCenter.nowPlayingInfo = nowPlayingInfo
    }

    @IBAction func startPlayingButtonPressed(_ sender: Any)
    {
        self.player.play()
    }

---

OLD ANSWER IOS 8.2:

Patrick's answer is totally right.

But i'm gonna write what i do for ios 8.2:

I add my app's info.plist required background modes like below:

And in my AppDelegate.h i add these imports:

#import <AVFoundation/AVFoundation.h>
#import <AudioToolbox/AudioToolbox.h>

Then in my AppDelegate.m i wrote application didFinishLaunchingWithOptionsthis exactly like below:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.

    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];

    return YES;
}

Now App keeps playing music even if screen is locked :)