Autoplay the next voice message if it is the next timeline item. (#6089)

ElementX/Sources/Services/AlertTones/NotificationToneManager.swift

@@ -263,15 +263,7 @@ nonisolated struct NotificationToneManager: NotificationToneManagerProtocol {
                             filename: "sound_01.caf")
     ].sorted()
     
-    private static let systemLocation = {
-        let systemRoot: URL
-        if let simulatorRoot = ProcessInfo.processInfo.environment["SIMULATOR_ROOT"] {
-            systemRoot = URL(filePath: simulatorRoot)
-        } else {
-            systemRoot = URL(filePath: "/")
-        }
-        return systemRoot.appending(components: "System", "Library", "Audio", "UISounds", directoryHint: .isDirectory)
-    }()
+    private static let systemLocation = URL.systemSoundsDirectory
     
     private static let bundledLocation: URL = {
         guard let url = Bundle.app.resourceURL else {

ElementX/Sources/Services/Audio/Player/AudioPlayer.swift

@@ -179,16 +179,19 @@ class AudioPlayer: NSObject, AudioPlayerProtocol {
     }
     
     private func addObservers() {
-        guard let internalAudioPlayer, let playerItem else {
+        // Deliberately not shadowing the properties, the observers compare against them to detect stale updates.
+        guard let currentAudioPlayer = internalAudioPlayer, let currentItem = playerItem else {
             return
         }
         
-        statusObserver = playerItem.observe(\.status, options: [.old, .new]) { [weak self] item, _ in
+        statusObserver = currentItem.observe(\.status, options: [.old, .new]) { [weak self] item, _ in
             // KVO fires on an arbitrary thread, hop to the main actor with the values we need.
             let status = item.status
             let error = item.error
             Task { @MainActor [weak self] in
-                guard let self else { return }
+                // Ignore an update that was queued before the content was replaced, it would leave
+                // the state out of sync with the item that is loaded now.
+                guard let self, item === playerItem else { return }
                 
                 switch status {
                 case .failed:
@@ -202,11 +205,11 @@ class AudioPlayer: NSObject, AudioPlayerProtocol {
             }
         }
         
-        rateObserver = internalAudioPlayer.observe(\.rate, options: [.old, .new]) { [weak self] player, _ in
+        rateObserver = currentAudioPlayer.observe(\.rate, options: [.old, .new]) { [weak self] player, _ in
             // KVO fires on an arbitrary thread, hop to the main actor with the values we need.
             let rate = player.rate
             Task { @MainActor [weak self] in
-                guard let self else { return }
+                guard let self, player === internalAudioPlayer else { return }
                 
                 if rate == 0 {
                     if isStopped {
@@ -220,7 +223,9 @@ class AudioPlayer: NSObject, AudioPlayerProtocol {
             }
         }
         
-        NotificationCenter.default.publisher(for: Notification.Name.AVPlayerItemDidPlayToEndTime)
+        NotificationCenter.default.publisher(for: Notification.Name.AVPlayerItemDidPlayToEndTime, object: currentItem)
+            // The notification isn't posted on the main thread, unlike the state updates it triggers.
+            .receive(on: DispatchQueue.main)
             .sink { [weak self] _ in
                 guard let self else { return }
                 setInternalState(.finishedPlaying)

ElementX/Sources/Services/Audio/Player/AudioPlayerState.swift

@@ -128,7 +128,6 @@ class AudioPlayerState: ObservableObject, Identifiable {
     
     private func subscribeToAudioPlayer(audioPlayer: AudioPlayerProtocol) {
         audioPlayerSubscription = audioPlayer.actions
-            .receive(on: DispatchQueue.main)
             .sink { [weak self] action in
                 guard let self else {
                     return

ElementX/Sources/Services/MediaPlayer/MediaPlayerProvider.swift

@@ -6,11 +6,14 @@
 // Please see LICENSE files in the repository root for full details.
 //
 
+import AVFoundation
 import Foundation
 
 class MediaPlayerProvider: MediaPlayerProviderProtocol {
     private lazy var audioPlayer = AudioPlayer()
     private var audioPlayerStates: [String: AudioPlayerState] = [:]
+    /// Held onto for the duration of the playback, an unowned player is silent.
+    private var soundEffectPlayer: AVAudioPlayer?
     
     var player: AudioPlayerProtocol {
         audioPlayer
@@ -55,6 +58,17 @@ class MediaPlayerProvider: MediaPlayerProviderProtocol {
         }
     }
     
+    /// Doesn't configure an audio session, so that it can be used alongside any existing player or session.
+    func play(soundEffect: SoundEffect) {
+        do {
+            let player = try AVAudioPlayer(contentsOf: soundEffect.fileURL)
+            soundEffectPlayer = player
+            player.play()
+        } catch {
+            MXLog.error("Failed playing the sound effect: \(error)")
+        }
+    }
+    
     // MARK: - Private
     
     private func audioPlayerStateID(for identifier: AudioPlayerStateIdentifier) -> String? {

ElementX/Sources/Services/MediaPlayer/MediaPlayerProviderProtocol.swift

@@ -8,6 +8,17 @@
 
 import Foundation
 
+enum SoundEffect {
+    /// A short, light blip.
+    case tink
+    
+    var fileURL: URL {
+        switch self {
+        case .tink: URL.systemSoundsDirectory.appending(component: "Tink.caf")
+        }
+    }
+}
+
 protocol MediaPlayerProviderProtocol {
     var player: AudioPlayerProtocol { get }
     
@@ -15,6 +26,10 @@ protocol MediaPlayerProviderProtocol {
     func register(audioPlayerState: AudioPlayerState)
     func unregister(audioPlayerState: AudioPlayerState)
     func detachAllStates(except exception: AudioPlayerState?) async
+    
+    /// Plays a short sound on top of whatever is already playing. It goes through the app's own
+    /// audio session, so unlike the sounds built into iOS it is heard in silent mode too.
+    func play(soundEffect: SoundEffect)
 }
 
 // sourcery: AutoMockable