feature: Add audio player listener feature on iOS

- update README.md and CHANGELOG.md

CHANGELOG.md

@@ -1,6 +1,6 @@
 ## 0.1.2
 
- * **Android** Added ability to receive notifications when a players `isPlaying` state changes.
+ * Added ability to receive notifications when a players `isPlaying` state changes.
 
 ## 0.1.1
 

README.md

@@ -101,17 +101,21 @@ If you found your way here because `ocarina` was recommended by [`twilio_program
   }
 ```
 
-## Android Audio Player State Listeners
+## Audio Player State Listeners
 
 This feature was also developed in concert with the ongoing development of the audio system for [`twilio_programmable_video`](https://pub.dev/packages/twilio_programmable_video), though it was designed to be agnostic to what other plugins you are using. As such, you can certainly add custom listeners via this mechanism to receive the same notifications. The only requirement is that they have the following signature:
 
+Android:
 ```kotlin
 (url: String, isPlaying: Boolean) -> Unit
 ```
 
-If you wish to use this feature with [`twilio_programmable_video`](https://pub.dev/packages/twilio_programmable_video), simply add the following to your `MainActivity.kt`.
+iOS
+```swift
+(_ url: String, _ isPlaying: Bool) -> Void
+```
 
-The benefit of using this feature with the[`twilio_programmable_video`](https://pub.dev/packages/twilio_programmable_video) is that it will enable that plugin to update the [Audio Focus](https://developer.android.com/guide/topics/media-apps/audio-focus) and usage of Bluetooth Sco based upon whether there are active audio players, in addition to an active call.
+If you wish to use this feature with [`twilio_programmable_video`](https://pub.dev/packages/twilio_programmable_video), simply add the following to your `MainActivity.kt`.
 
 ```kotlin
     private lateinit var PACKAGE_ID: String
@@ -127,4 +131,30 @@ The benefit of using this feature with the[`twilio_programmable_video`](https://
         super.cleanUpFlutterEngine(flutterEngine)
         OcarinaPlugin.removeListener(PACKAGE_ID)
     }
+```
+The benefit of using this feature (on Android) with the [`twilio_programmable_video`](https://pub.dev/packages/twilio_programmable_video) is that it will enable that plugin to update the [Audio Focus](https://developer.android.com/guide/topics/media-apps/audio-focus) and usage of Bluetooth Sco based upon whether there are active audio players, in addition to an active call.
+
+Alternatively, you can use it with your own listener for your own purposes.
+
+This feature has not been integrated with `twilio_programmable_video` on iOS, out of preference for usage of the `AVAudioEngineDevice` as a delegate for `ocarina`.
+
+If you wish to use this feature on iOS, add the following to  your `AppDelegate.swift`:
+
+```swift
+    let bundleID = Bundle.main.bundleIdentifier
+
+    override func application(
+        _ application: UIApplication,
+        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+    ) -> Bool {
+        SwiftOcarinaPlugin.addListener(bundleID!, ocarinaListener)
+    }
+
+    override func applicationWillTerminate(_ application: UIApplication) {
+        SwiftOcarinaPlugin.removeListener(bundleID!)
+    }
+
+    func ocarinaListener(_ id: String, _ isPlaying: Bool) {
+        // do things
+    }
 ```

ios/Classes/SwiftOcarinaPlugin.swift

@@ -11,14 +11,19 @@ protocol Player {
     func seek(position: Int) -> Void
     func volume(volume: Double) -> Void
     func position() -> Int64?
+    func addListener() -> Void
+    func removeListener() -> Void
 }
 
 class LoopPlayer: Player {
     let player: AVQueuePlayer
     let playerLooper: AVPlayerLooper
+    var listener: NSKeyValueObservation?
+    let url: String
 
     required init(url: String, volume: Double) {
-        let asset = AVAsset(url: URL(fileURLWithPath: url ))
+        self.url = url
+        let asset = AVAsset(url: URL(fileURLWithPath: url))
 
         let playerItem = AVPlayerItem(asset: asset)
 
@@ -63,15 +68,39 @@ class LoopPlayer: Player {
 
         return positionInMillis
     }
+
+    func addListener() -> Void {
+        if listener == nil {
+            listener = player.observe(\AVQueuePlayer.rate, options: [.old, .new]) { [unowned self] _, change in
+                if let newValue = change.newValue,
+                   let oldValue = change.oldValue,
+                   newValue != oldValue {
+                    SwiftOcarinaPlugin.notifyListeners(url: url, isPlaying: newValue > 0)
+                }
+            }
+        }
+    }
+
+    func removeListener() -> Void {
+        listener?.invalidate()
+        listener = nil
+    }
 }
 
 class SinglePlayer: Player {
-    var player: AVAudioPlayer
+    let player: AVPlayer
+    var listener: NSKeyValueObservation?
+    let url: String
 
     required init(url: String, volume: Double) {
-        try! self.player = AVAudioPlayer(contentsOf: URL(fileURLWithPath: url ))
+        self.url = url
+        let asset = AVAsset(url: URL(fileURLWithPath: url))
+
+        let playerItem = AVPlayerItem(asset: asset)
+
+        player = AVPlayer(playerItem: playerItem)
+
         self.player.volume = Float(volume)
-        self.player.prepareToPlay()
     }
 
     func play() {
@@ -89,21 +118,44 @@ class SinglePlayer: Player {
 
     func stop() {
         pause()
+        seek(position: 0)
     }
 
     func seek(position: Int) {
-        player.currentTime = Float64(position) / 1000
+        player.seek(to: CMTimeMakeWithSeconds(Float64(position / 1000), preferredTimescale: Int32(NSEC_PER_SEC)))
     }
 
     func volume(volume: Double) {
         player.volume = Float(volume)
     }
 
     func position() -> Int64? {
-        let positionInMillis = Int64(player.currentTime * 1000)
+        guard let value = player.currentItem?.currentTime().value,
+              let timescale = player.currentItem?.currentTime().timescale else {
+            return nil
+        }
+
+        let positionInMillis = Int64((Float64(value) / Float64(timescale)) * 1000)
 
         return positionInMillis
     }
+
+    func addListener() -> Void {
+        if listener == nil {
+            listener = player.observe(\AVPlayer.rate, options: [.old, .new]) { [unowned self] _, change in
+                if let newValue = change.newValue,
+                   let oldValue = change.oldValue,
+                   newValue != oldValue {
+                    SwiftOcarinaPlugin.notifyListeners(url: url, isPlaying: newValue > 0)
+                }
+            }
+        }
+    }
+
+    func removeListener() -> Void {
+        listener?.invalidate()
+        listener = nil
+    }
 }
 
 class PlayerDelegate {
@@ -166,7 +218,7 @@ class PlayerDelegate {
     func position(_ id: Int) -> Int64 {
         return positionDelegate(id)
     }
-    
+
     init(load: @escaping LoadDelegate, dispose: @escaping DisposeDelegate, play: @escaping PlayDelegate, pause: @escaping PauseDelegate, resume: @escaping ResumeDelegate, stop: @escaping StopDelegate, volume: @escaping VolumeDelegate, seek: @escaping SeekDelegate, position: @escaping PositionDelegate) {
         loadDelegate = load
         disposeDelegate = dispose
@@ -190,8 +242,11 @@ public typealias VolumeDelegate = (_ id: Int, _ volume: Double) -> Void
 public typealias SeekDelegate = (_ id: Int, _ positionInMillis: Int) -> Void
 public typealias PositionDelegate = (_ id: Int) -> Int64
 
+public typealias Listener = (_ url: String, _ isPlaying: Bool) -> Void
+
 public class SwiftOcarinaPlugin: NSObject, FlutterPlugin {
     static var players = [Int: Player]()
+    static var listeners = [String: Listener]()
     static var id: Int = 0;
     static var delegate: PlayerDelegate?
     var registrar: FlutterPluginRegistrar? = nil
@@ -207,6 +262,32 @@ public class SwiftOcarinaPlugin: NSObject, FlutterPlugin {
         delegate = PlayerDelegate(load: load, dispose: dispose, play: play, pause: pause, resume: resume, stop: stop, volume: volume, seek: seek, position: position)
     }
 
+    public static func notifyListeners(url: String, isPlaying: Bool) {
+        listeners.values.forEach { listener in
+            listener(url, isPlaying)
+        }
+    }
+
+    public static func addListener(_ id: String, _ listener: @escaping Listener) {
+        NSLog("SwiftOcarinaPlugin::addListener => id: \(id)")
+        if listeners.isEmpty && !players.isEmpty {
+            players.values.forEach { player in
+                player.addListener()
+            }
+        }
+
+        listeners[id] = listener
+    }
+
+    public static func removeListener(_ id: String) {
+        listeners.removeValue(forKey: id)
+        if listeners.isEmpty {
+            players.values.forEach { player in
+                player.removeListener()
+            }
+        }
+    }
+
     public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
         if (call.method == "load") {
             load(call, result: result)
@@ -269,6 +350,10 @@ public class SwiftOcarinaPlugin: NSObject, FlutterPlugin {
 
             SwiftOcarinaPlugin.id = SwiftOcarinaPlugin.id + 1
 
+            if let player = SwiftOcarinaPlugin.players[id], !SwiftOcarinaPlugin.listeners.isEmpty {
+                player.addListener()
+            }
+
             result(id)
         }
     }