Start playing sound in background on iOS?

Question

I\'m trying to do something similar to Tile.app. When it shows a notification, it plays a sound. That seems simple enough-- use UILocalNotification and include

Answer 1

Actually you can use one of AudioServices... functions

• AudioServicesPlaySystemSound
• AudioServicesPlayAlertSound
• AudioServicesPlaySystemSoundWithCompletion

to start playing sound in background.

I'm not sure about length of sound that can be submitted to AudioServicesCreateSystemSoundID because I'm checked only with short looped sound for ringing but this API not tied to notification so possible can overpass 30 second limit.

EDIT: App still requires audio in UIBackgroundModes to play in background

Cut from my test project appDelegate, iOS 9.3.1

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // test sound in foreground.
    registerAndPlaySound()

    return true
}

func applicationDidEnterBackground(application: UIApplication) {
    var task =  UIBackgroundTaskInvalid
    task = application.beginBackgroundTaskWithName("time for music") {
        application.endBackgroundTask(task)
    }
    // dispatch not required, it's just to simulate "deeper" background  
    let delayTime = dispatch_time(DISPATCH_TIME_NOW, Int64(5 * Double(NSEC_PER_SEC)))

    dispatch_after(delayTime, dispatch_get_main_queue()) {
        self.registerAndPlaySound()
    }
}

func registerAndPlaySound() {
    var soundId: SystemSoundID = 0

    let bundle = NSBundle.mainBundle()
    guard let soundUrl = bundle.URLForResource("InboundCallRing", withExtension: "wav") else {
        return
    }
    AudioServicesCreateSystemSoundID(soundUrl, &soundId)

    AudioServicesPlayAlertSound(soundId)
}

Update

There I used beginBackgroundTask to start sound only as simplest way to execute code in background in another project similar code to registerAndPlaySound was called from PushKit callback without background task.