Detect volume button press

Question

Volume button notification function is not being called.

Code:

func listenVolumeButton(){     // Option #1     NSNotificationCenter.defaultCenter().addObserver(self, selector: "volumeChanged:", name: "AVSystemController_SystemVolumeDidChangeNotification", object: nil)     // Option #2     var audioSession = AVAudioSession()     audioSession.setActive(true, error: nil)     audioSession.addObserver(self, forKeyPath: "volumeChanged", options: NSKeyValueObservingOptions.New, context: nil) }  override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {     if keyPath == "volumeChanged"{         print("got in here")     } }  func volumeChanged(notification: NSNotification){    print("got in here") } 

listenVolumeButton() is being called in viewWillAppear

The code is not getting to the print statement "got in here", in either case.

I am trying two different ways to do it, neither way is working.

I have followed this: Detect iPhone Volume Button Up Press?

Answer 1

Using the second method, the value of the key path should be "outputVolume". That is the property we are observing. So change the code to,

var outputVolumeObserve: NSKeyValueObservation? let audioSession = AVAudioSession.sharedInstance()  func listenVolumeButton() {     do {         try audioSession.setActive(true)     } catch {}      outputVolumeObserve = audioSession.observe(\.outputVolume) { (audioSession, changes) in         /// TODOs     } }