Wie Sie sehen, streame ich eine Audiosendung. Aber wenn ich die Home-Taste drücke und die App verlasse, stoppt das Streaming oder ich kann nicht hören. Wie kann ich das Streaming im Hintergrund fortsetzen und es vom Sperrbildschirm aus anhören?

ViewController.Swift

import UIKit
import AVFoundation
import MediaPlayer
import GoogleMobileAds


    class ViewController: UIViewController, GADInterstitialDelegate {

        @IBOutlet weak var exitMapButton: UIButton!
        @IBOutlet weak var radarMap: UIWebView!
        var interstitial: GADInterstitial!
        func createAndLoadInterstitial() -> GADInterstitial {
            var interstitial = GADInterstitial(adUnitID: "ca-app-pub-5378899862041789/2782958552")
            interstitial.delegate = self
            interstitial.loadRequest(GADRequest())
            return interstitial
        }

        func getAd(){
            if (self.interstitial.isReady)
            {
                self.interstitial.presentFromRootViewController(self)
                self.interstitial = self.createAndLoadInterstitial()
            }
        }
        @IBOutlet weak var ataturkButton: UIButton!
        @IBOutlet weak var sabihaButton: UIButton!
        @IBOutlet weak var esenbogaButton: UIButton!
        @IBOutlet weak var weatherButton: UIButton!
        @IBOutlet weak var statusLabel: UILabel!
        @IBOutlet weak var playButton: UIButton!
        @IBOutlet weak var webViewButton: UIButton!
        var googleBannerView: GADBannerView!
override func viewDidLoad() {
            super.viewDidLoad()
        }
class PlayerAv {
            var audioLink: String?
            var player: AVPlayer
            init(link: String) {
                self.audioLink = link
                self.player = AVPlayer(URL: NSURL(string: link))
            }
        }
        var myPlayer = PlayerAv(link: "http://www.liveatc.net/play/ltba.pls")
        var setTowerState = ""

        @IBAction func sliderValueChanged(sender: UISlider) {
            var currentValue = Float(sender.value)
            println(currentValue)
            myPlayer.player.volume = currentValue
        }
        @IBAction func getWeatherWindow(sender: AnyObject) {
            UIApplication.sharedApplication().openURL(NSURL(string: "http://www.aviationweather.gov/adds/metars/?station_ids=ltac&std_trans=standard&chk_metars=on&hoursStr=most+recent+only&chk_tafs=on&submitmet=Submit")!)
            println("Directed to weather page")
        }
        @IBAction func changeToAtaturk() {
            myPlayer.player.pause()
            myPlayer = PlayerAv(link: "http://www.liveatc.net/play/ltba.pls")
            myPlayer.audioLink == ""
            println("\(myPlayer.audioLink!)--a")
            playButton.setTitle("Pause", forState: UIControlState.Normal)
            myPlayer.player.play()
            setTowerState = "ataturk"
            statusLabel.text = "Status: Playing, LTBA"
        }
        @IBAction func changeToEsenboga() {
            myPlayer.player.pause()
            myPlayer = PlayerAv(link: "http://www.liveatc.net/play/ltac.pls")
            println("\(myPlayer.audioLink!)--a")
            playButton.setTitle("Pause", forState: UIControlState.Normal)
            myPlayer.player.play()
            setTowerState = "esenboga"
            statusLabel.text = "Status: Playing, LTAC"
        }
        @IBAction func changeToSabiha() {
            myPlayer.player.pause()
            myPlayer = PlayerAv(link: "http://www.liveatc.net/play/ltfj.pls")
            println("\(myPlayer.audioLink!)--a")
            playButton.setTitle("Pause", forState: UIControlState.Normal)
            myPlayer.player.play()
            setTowerState = "sabiha"
            statusLabel.text = "Status: Playing, LTFJ"
        }
        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
        }
        @IBAction func playButtonPressed(sender: AnyObject) {
            toggle()
        }
        func toggle() {
            if playButton.titleLabel?.text == "Play" {
                playRadio()
                println("Playing")
                statusLabel.text = "Status: Playing"
            } else {
                pauseRadio()
                println("Paused")
                statusLabel.text = "Status: Paused"
            }
        }
        func playRadio() {
            myPlayer.player.play()
            playButton.setTitle("Pause", forState: UIControlState.Normal)   
        }
        func pauseRadio() {
            myPlayer.player.pause()
            playButton.setTitle("Play", forState: UIControlState.Normal)
        }
    }