Swift: changing AVAudioSession route (voice from speaker to headphone and vice versa)

 NSNotificationCenter.defaultCenter().addObserver(self, selector: "handleAVAudioSessionRouteChange:", name: AVAudioSessionRouteChangeNotification, object: nil)

@objc private func handleAVAudioSessionRouteChange(notification : NSNotification) {

        

        println("change route \(notification.userInfo)")

        let audioSession = AVAudioSession.sharedInstance()

        var error : NSError?

        let audioRouteChangeReason = notification.userInfo![AVAudioSessionRouteChangeReasonKey] as UInt

        

        switch audioRouteChangeReason {

        case AVAudioSessionRouteChangeReason.NewDeviceAvailable.rawValue:

            println("headphone plugged in")

        audioSession.overrideOutputAudioPort(AVAudioSessionPortOverride.None, error: &error)

        case AVAudioSessionRouteChangeReason.OldDeviceUnavailable.rawValue:

            println("headphone pulled out")

            audioSession.overrideOutputAudioPort(AVAudioSessionPortOverride.Speaker, error: &error)

        default:

            break

        }

    }