Detect volume button press
The code above won't work in Swift 3, in that case, try this:
func listenVolumeButton() {
do {
try audioSession.setActive(true)
} catch {
print("some error")
}
audioSession.addObserver(self, forKeyPath: "outputVolume", options: NSKeyValueObservingOptions.new, context: nil)
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if keyPath == "outputVolume" {
print("got in here")
}
}
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
}
}
With this code you can listen whenever the user taps the volume hardware button.
class VolumeListener {
static let kVolumeKey = "volume"
static let shared = VolumeListener()
private let kAudioVolumeChangeReasonNotificationParameter = "AVSystemController_AudioVolumeChangeReasonNotificationParameter"
private let kAudioVolumeNotificationParameter = "AVSystemController_AudioVolumeNotificationParameter"
private let kExplicitVolumeChange = "ExplicitVolumeChange"
private let kSystemVolumeDidChangeNotificationName = NSNotification.Name(rawValue: "AVSystemController_SystemVolumeDidChangeNotification")
private var hasSetup = false
func start() {
guard !self.hasSetup else {
return
}
self.setup()
self.hasSetup = true
}
private func setup() {
guard let rootViewController = UIApplication.shared.windows.first?.rootViewController else {
return
}
let volumeView = MPVolumeView(frame: CGRect.zero)
volumeView.clipsToBounds = true
rootViewController.view.addSubview(volumeView)
NotificationCenter.default.addObserver(
self,
selector: #selector(self.volumeChanged),
name: kSystemVolumeDidChangeNotificationName,
object: nil
)
volumeView.removeFromSuperview()
}
@objc func volumeChanged(_ notification: NSNotification) {
guard let userInfo = notification.userInfo,
let volume = userInfo[kAudioVolumeNotificationParameter] as? Float,
let changeReason = userInfo[kAudioVolumeChangeReasonNotificationParameter] as? String,
changeReason == kExplicitVolumeChange
else {
return
}
NotificationCenter.default.post(name: "volumeListenerUserDidInteractWithVolume", object: nil,
userInfo: [VolumeListener.kVolumeKey: volume])
}
}
And to listen you just need to add the observer:
NotificationCenter.default.addObserver(self, selector: #selector(self.userInteractedWithVolume),
name: "volumeListenerUserDidInteractWithVolume", object: nil)
You can access the volume value by checking the userInfo:
@objc private func userInteractedWithVolume(_ notification: Notification) {
guard let volume = notification.userInfo?[VolumeListener.kVolumeKey] as? Float else {
return
}
print("volume: \(volume)")
}