iOs 8, start playing sound when in the background, alarm clock app

问题

I know there are many questions on SOF, but this is the "newest" one. The thing is, I'm trying to create and alarm app, and I know for a fact that there are alarm apps out there that works perfectly ( somehow ), even if the app is not running and is in the background.

My question is: how do you start playing sound after your app is already in the background ??

UILocalNotification is great, but you'll only get application:(_:didReceiveLocalNotification:) after the user has already clicked on your notification, so playing sound using AVAudioPlayer didn't work, i want to play sound regardless weather the user clicks on it or doesn't. Of course with Required background modes: App plays audio or streams audio/video using AirPlay in info.plist already set. Once the music starts playing, it keeps playing even if i go to the background.

I don't want to use UILocalNotificaation sound coz it's limited to 30 secs and only the able to play the sounds that are bundled with the application.

Any insights ? thoughts ??

Sample code:

    var notif = UILocalNotification()
    notif.fireDate = self.datePicker.date
    notif.alertBody = "test"
    UIApplication.sharedApplication().scheduleLocalNotification(notif)

the above code gets called when the user selects and alarm and clicks save.

and here's what's happening in AppDelegate:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
    NSLog("launched")
    application.registerUserNotificationSettings(UIUserNotificationSettings(forTypes: UIUserNotificationType.Sound | UIUserNotificationType.Alert |
        UIUserNotificationType.Badge, categories: nil
        ))
    AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)
    AVAudioSession.sharedInstance().setActive(true, error: nil)

    self.sound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("sound", ofType: "caf"))
    self.audioPlayer = AVAudioPlayer(contentsOfURL: sound, error: nil)

    return true
}

func application(application: UIApplication!, didReceiveLocalNotification notification: UILocalNotification!){
    audioPlayer.play()
    NSLog("received local notif")


}

You need to hold a strong reference to the AVAudioPlayer btw, so it won't get released, and the audioplayer.play() won't do anything...

回答1:

Finally, I managed to do it with NSTimer.

func applicationWillResignActive(application: UIApplication) {
    var timer = NSTimer(fireDate: NSDate(timeIntervalSinceNow: 20), interval: 60.0, target: self, selector: Selector("playAlarm"), userInfo: nil, repeats: false)
    NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSDefaultRunLoopMode)
}
func playAlarm() {
    self.sound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("sound", ofType: "caf"))
    self.audioPlayer = AVAudioPlayer(contentsOfURL: sound, error: nil)
    audioPlayer.play()
}

and somewhere else a UILocalNotification is synced with this timer, for a good user experience.

Although I'm not sure if this would go through apple, but I don't see any reason why it wouldn't :\

来源：https://stackoverflow.com/questions/24749150/ios-8-start-playing-sound-when-in-the-background-alarm-clock-app

标签

ios

audio

swift

alarm