feat: Handle route change notifications

ios/App/Shared/player/AudioPlayer.swift

@@ -71,7 +71,7 @@ class AudioPlayer: NSObject {
         }
         
         // Listen to player events
-        self.setupInteruptionNotification()
+        self.setupAudioSessionNotifications()
         self.audioPlayer.addObserver(self, forKeyPath: #keyPath(AVPlayer.rate), options: .new, context: &playerContext)
         self.audioPlayer.addObserver(self, forKeyPath: #keyPath(AVPlayer.currentItem), options: .new, context: &playerContext)
         
@@ -120,7 +120,7 @@ class AudioPlayer: NSObject {
             print(error)
         }
         
-        self.removeInteruptionNotification()
+        self.removeAudioSessionNotifications()
         DispatchQueue.runOnMainQueue {
             UIApplication.shared.endReceivingRemoteControlEvents()
         }
@@ -148,12 +148,14 @@ class AudioPlayer: NSObject {
         return 0
     }
     
-    private func setupInteruptionNotification() {
+    private func setupAudioSessionNotifications() {
         NotificationCenter.default.addObserver(self, selector: #selector(handleInteruption), name: AVAudioSession.interruptionNotification, object: AVAudioSession.sharedInstance())
+        NotificationCenter.default.addObserver(self, selector: #selector(handleRouteChange), name: AVAudioSession.routeChangeNotification, object: AVAudioSession.sharedInstance())
     }
     
-    private func removeInteruptionNotification() {
+    private func removeAudioSessionNotifications() {
         NotificationCenter.default.removeObserver(self, name: AVAudioSession.interruptionNotification, object: AVAudioSession.sharedInstance())
+        NotificationCenter.default.removeObserver(self, name: AVAudioSession.routeChangeNotification, object: AVAudioSession.sharedInstance())
     }
     
     private func setupTimeObserver() {
@@ -598,7 +600,7 @@ class AudioPlayer: NSObject {
         }
     }
     
-    // MARK: - iOS audio interupt notifications
+    // MARK: - iOS audio session notifications
     @objc private func handleInteruption(notification: Notification) {
         guard let userInfo = notification.userInfo,
             let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
@@ -617,6 +619,38 @@ class AudioPlayer: NSObject {
         }
     }
     
+    @objc private func handleRouteChange(notification: Notification) {
+        guard let userInfo = notification.userInfo,
+            let reasonValue = userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt,
+            let reason = AVAudioSession.RouteChangeReason(rawValue: reasonValue) else {
+                return
+        }
+        
+        switch reason {
+        case .newDeviceAvailable: // New device found.
+            let session = AVAudioSession.sharedInstance()
+            let headphonesConnected = hasHeadphones(in: session.currentRoute)
+            if headphonesConnected {
+                // We should just let things be, as it's okay to go from speaker to headphones
+            }
+        case .oldDeviceUnavailable: // Old device removed.
+            if let previousRoute = userInfo[AVAudioSessionRouteChangePreviousRouteKey] as? AVAudioSessionRouteDescription {
+                let headphonesWereConnected = hasHeadphones(in: previousRoute)
+                if headphonesWereConnected {
+                    // Removing headphones we should pause instead of keeping on playing
+                    self.pause()
+                }
+            }
+        
+        default: ()
+        }
+    }
+    
+    private func hasHeadphones(in routeDescription: AVAudioSessionRouteDescription) -> Bool {
+        // Filter the outputs to only those with a port type of headphones.
+        return !routeDescription.outputs.filter({$0.portType == .headphones}).isEmpty
+    }
+    
     // MARK: - Now playing
     private func setupRemoteTransportControls() {
         DispatchQueue.runOnMainQueue {