fix: fixed bad null safety implementation

Author: juicycleff

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.2.1
+
+* Improved nullsafety
+
 ## 4.2.0
 
 * Null safe merged to master

lib/src/controller.dart

@@ -2,9 +2,6 @@ part of flutter_unity_widget;
 
 typedef void UnityCreatedCallback(UnityWidgetController controller);
 
-final UnityViewFlutterPlatform _unityViewFlutterPlatform =
-    UnityViewFlutterPlatform.instance;
-
 class UnityWidgetController {
   final _UnityWidgetState _unityWidgetState;
 
@@ -25,7 +22,7 @@ class UnityWidgetController {
   /// in [UnityWidget.onUnityCreated] callback.
   static Future<UnityWidgetController> init(
       int id, _UnityWidgetState unityWidgetState) async {
-    await _unityViewFlutterPlatform.init(id);
+    await UnityViewFlutterPlatform.instance.init(id);
     return UnityWidgetController._(
       unityWidgetState,
       unityId: id,
@@ -34,30 +31,31 @@ class UnityWidgetController {
 
   @visibleForTesting
   MethodChannel? get channel {
-    if (_unityViewFlutterPlatform is MethodChannelUnityViewFlutter) {
-      return (_unityViewFlutterPlatform as MethodChannelUnityViewFlutter)
+    if (UnityViewFlutterPlatform.instance is MethodChannelUnityViewFlutter) {
+      return (UnityViewFlutterPlatform.instance
+              as MethodChannelUnityViewFlutter)
           .channel(unityId);
     }
     return null;
   }
 
   void _connectStreams(int unityId) {
     if (_unityWidgetState.widget.onUnityMessage != null) {
-      _onUnityMessageSub = _unityViewFlutterPlatform
+      _onUnityMessageSub = UnityViewFlutterPlatform.instance
           .onUnityMessage(unityId: unityId)
           .listen((UnityMessageEvent e) =>
               _unityWidgetState.widget.onUnityMessage!(e.value));
     }
 
     if (_unityWidgetState.widget.onUnitySceneLoaded != null) {
-      _onUnitySceneLoadedSub = _unityViewFlutterPlatform
+      _onUnitySceneLoadedSub = UnityViewFlutterPlatform.instance
           .onUnitySceneLoaded(unityId: unityId)
           .listen((UnitySceneLoadedEvent e) =>
               _unityWidgetState.widget.onUnitySceneLoaded!(e.value));
     }
 
     if (_unityWidgetState.widget.onUnityUnloaded != null) {
-      _onUnityUnloadedSub = _unityViewFlutterPlatform
+      _onUnityUnloadedSub = UnityViewFlutterPlatform.instance
           .onUnityUnloaded(unityId: unityId)
           .listen((_) => _unityWidgetState.widget.onUnityUnloaded!());
     }
@@ -67,7 +65,7 @@ class UnityWidgetController {
   /// Returns `true` if unity player is ready.
   Future<bool?>? isReady() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.isReady(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.isReady(unityId: unityId);
     }
     return null;
   }
@@ -76,7 +74,7 @@ class UnityWidgetController {
   /// Returns `true` if unity player is paused.
   Future<bool?>? isPaused() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.isPaused(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.isPaused(unityId: unityId);
     }
     return null;
   }
@@ -85,7 +83,7 @@ class UnityWidgetController {
   /// Returns `true` if unity player is loaded.
   Future<bool?>? isLoaded() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.isLoaded(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.isLoaded(unityId: unityId);
     }
     return null;
   }
@@ -94,7 +92,7 @@ class UnityWidgetController {
   /// Returns `true` if unity player is in background.
   Future<bool?>? inBackground() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.inBackground(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.inBackground(unityId: unityId);
     }
     return null;
   }
@@ -104,7 +102,8 @@ class UnityWidgetController {
   /// Returns `true` if unity player was created succesfully.
   Future<bool?>? create() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.createUnityPlayer(unityId: unityId);
+      return UnityViewFlutterPlatform.instance
+          .createUnityPlayer(unityId: unityId);
     }
     return null;
   }
@@ -118,7 +117,7 @@ class UnityWidgetController {
   /// ```
   Future<void>? postMessage(String gameObject, methodName, message) {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.postMessage(
+      return UnityViewFlutterPlatform.instance.postMessage(
         unityId: unityId,
         gameObject: gameObject,
         methodName: methodName,
@@ -138,7 +137,7 @@ class UnityWidgetController {
   Future<void>? postJsonMessage(
       String gameObject, String methodName, Map<String, dynamic> message) {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.postJsonMessage(
+      return UnityViewFlutterPlatform.instance.postJsonMessage(
         unityId: unityId,
         gameObject: gameObject,
         methodName: methodName,
@@ -151,15 +150,15 @@ class UnityWidgetController {
   /// Pause the unity in-game player with this method
   Future<void>? pause() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.pausePlayer(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.pausePlayer(unityId: unityId);
     }
     return null;
   }
 
   /// Resume the unity in-game player with this method idf it is in a paused state
   Future<void>? resume() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.resumePlayer(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.resumePlayer(unityId: unityId);
     }
     return null;
   }
@@ -168,7 +167,8 @@ class UnityWidgetController {
   /// It works for Android and iOS is WIP
   Future<void>? openInNativeProcess() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.openInNativeProcess(unityId: unityId);
+      return UnityViewFlutterPlatform.instance
+          .openInNativeProcess(unityId: unityId);
     }
     return null;
   }
@@ -177,15 +177,15 @@ class UnityWidgetController {
   /// iOS is WIP. For more information please read [Unity Docs](https://docs.unity3d.com/2020.2/Documentation/Manual/UnityasaLibrary.html)
   Future<void>? unload() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.unloadPlayer(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.unloadPlayer(unityId: unityId);
     }
     return null;
   }
 
   /// Quits unity player. Note that this kills the current flutter process, thus quiting the app
   Future<void>? quit() {
     if (!_unityWidgetState.widget.enablePlaceholder) {
-      return _unityViewFlutterPlatform.quitPlayer(unityId: unityId);
+      return UnityViewFlutterPlatform.instance.quitPlayer(unityId: unityId);
     }
     return null;
   }
@@ -203,7 +203,7 @@ class UnityWidgetController {
 
   void dispose() {
     _cancelSubscriptions();
-    _unityViewFlutterPlatform.dispose(unityId: unityId);
+    UnityViewFlutterPlatform.instance.dispose(unityId: unityId);
   }
 }
 

lib/src/device_method.dart

@@ -1,27 +1,56 @@
 part of flutter_unity_widget;
 
+/// Error thrown when an unknown unity ID is provided to a method channel API.
+class UnknownUnityIDError extends Error {
+  /// Creates an assertion error with the provided [unityId] and optional
+  /// [message].
+  UnknownUnityIDError(this.unityId, [this.message]);
+
+  /// The unknown ID.
+  final int unityId;
+
+  /// Message describing the assertion error.
+  final Object? message;
+
+  String toString() {
+    if (message != null) {
+      return "Unknown unity ID $unityId: ${Error.safeToString(message)}";
+    }
+    return "Unknown unity ID $unityId";
+  }
+}
+
 class MethodChannelUnityViewFlutter extends UnityViewFlutterPlatform {
   // Every method call passes the int unityId
-  final Map<int, MethodChannel?> _channels = {};
+  late final Map<int, MethodChannel> _channels = {};
 
   /// Accesses the MethodChannel associated to the passed unityId.
-  MethodChannel? channel(int unityId) {
-    return _channels[unityId];
+  MethodChannel channel(int unityId) {
+    MethodChannel? channel = _channels[unityId];
+    if (channel == null) {
+      throw UnknownUnityIDError(unityId);
+    }
+    return channel;
   }
 
-  /// Initializes the platform interface with [id].
-  ///
-  /// This method is called when the plugin is first initialized.
-  @override
-  Future<void> init(int unityId) {
-    MethodChannel? channel;
-    if (!_channels.containsKey(unityId)) {
+  MethodChannel ensureChannelInitialized(int unityId) {
+    MethodChannel? channel = _channels[unityId];
+    if (channel == null) {
       channel = MethodChannel('plugin.xraph.com/unity_view_$unityId');
       channel.setMethodCallHandler(
           (MethodCall call) => _handleMethodCall(call, unityId));
       _channels[unityId] = channel;
     }
-    return channel!.invokeMethod<void>('unity#waitForUnity');
+    return channel;
+  }
+
+  /// Initializes the platform interface with [id].
+  ///
+  /// This method is called when the plugin is first initialized.
+  @override
+  Future<void> init(int unityId) {
+    MethodChannel channel = ensureChannelInitialized(unityId);
+    return channel.invokeMethod<void>('unity#waitForUnity');
   }
 
   /// Dispose of the native resources.
@@ -65,27 +94,27 @@ class MethodChannelUnityViewFlutter extends UnityViewFlutterPlatform {
 
   @override
   Future<bool?> isPaused({required int unityId}) async {
-    return await channel(unityId)!.invokeMethod('unity#isPaused');
+    return await channel(unityId).invokeMethod('unity#isPaused');
   }
 
   @override
   Future<bool?> isReady({required int unityId}) async {
-    return await channel(unityId)!.invokeMethod('unity#isReady');
+    return await channel(unityId).invokeMethod('unity#isReady');
   }
 
   @override
   Future<bool?> isLoaded({required int unityId}) async {
-    return await channel(unityId)!.invokeMethod('unity#isLoaded');
+    return await channel(unityId).invokeMethod('unity#isLoaded');
   }
 
   @override
   Future<bool?> inBackground({required int unityId}) async {
-    return await channel(unityId)!.invokeMethod('unity#inBackground');
+    return await channel(unityId).invokeMethod('unity#inBackground');
   }
 
   @override
   Future<bool?> createUnityPlayer({required int unityId}) async {
-    return await channel(unityId)!.invokeMethod('unity#createPlayer');
+    return await channel(unityId).invokeMethod('unity#createPlayer');
   }
 
   @override
@@ -170,7 +199,7 @@ class MethodChannelUnityViewFlutter extends UnityViewFlutterPlatform {
       required String gameObject,
       required String methodName,
       required String message}) async {
-    await channel(unityId)!.invokeMethod('unity#postMessage', <String, dynamic>{
+    await channel(unityId).invokeMethod('unity#postMessage', <String, dynamic>{
       'gameObject': gameObject,
       'methodName': methodName,
       'message': message,
@@ -183,7 +212,7 @@ class MethodChannelUnityViewFlutter extends UnityViewFlutterPlatform {
       required String gameObject,
       required String methodName,
       required Map message}) async {
-    await channel(unityId)!.invokeMethod('unity#postMessage', <String, dynamic>{
+    await channel(unityId).invokeMethod('unity#postMessage', <String, dynamic>{
       'gameObject': gameObject,
       'methodName': methodName,
       'message': json.encode(message),
@@ -192,26 +221,26 @@ class MethodChannelUnityViewFlutter extends UnityViewFlutterPlatform {
 
   @override
   Future<void> pausePlayer({required int unityId}) async {
-    await channel(unityId)!.invokeMethod('unity#pausePlayer');
+    await channel(unityId).invokeMethod('unity#pausePlayer');
   }
 
   @override
   Future<void> resumePlayer({required int unityId}) async {
-    await channel(unityId)!.invokeMethod('unity#resumePlayer');
+    await channel(unityId).invokeMethod('unity#resumePlayer');
   }
 
   @override
   Future<void> openInNativeProcess({required int unityId}) async {
-    await channel(unityId)!.invokeMethod('unity#openInNativeProcess');
+    await channel(unityId).invokeMethod('unity#openInNativeProcess');
   }
 
   @override
   Future<void> unloadPlayer({required int unityId}) async {
-    await channel(unityId)!.invokeMethod('unity#unloadPlayer');
+    await channel(unityId).invokeMethod('unity#unloadPlayer');
   }
 
   @override
   Future<void> quitPlayer({required int unityId}) async {
-    await channel(unityId)!.invokeMethod('unity#quitPlayer');
+    await channel(unityId).invokeMethod('unity#quitPlayer');
   }
 }

lib/src/unity_view.dart

@@ -71,7 +71,7 @@ class _UnityWidgetState extends State<UnityWidget> {
           Text('Placeholder mode enabled, no native code will be called');
     }
 
-    return _unityViewFlutterPlatform.buildView(
+    return UnityViewFlutterPlatform.instance.buildView(
         creationParams,
         widget.gestureRecognizers,
         onPlatformViewCreated,
@@ -81,7 +81,10 @@ class _UnityWidgetState extends State<UnityWidget> {
   Future<void> onPlatformViewCreated(int id) async {
     final controller = await UnityWidgetController.init(id, this);
     _controller.complete(controller);
-    widget.onUnityCreated(controller);
+    final UnityCreatedCallback? onUnityCreated = widget.onUnityCreated;
+    if (onUnityCreated != null) {
+      onUnityCreated(controller);
+    }
     print('*********************************************');
     print('** flutter unity controller setup complete **');
     print('*********************************************');

pubspec.yaml

@@ -1,6 +1,6 @@
 name: flutter_unity_widget
 description: Flutter Unity 3D widget for embedding Unity game scenes in flutter. This library now supports Unity as a Library.
-version: 4.2.0
+version: 4.2.1
 #authors:
 #  - Rex Raphael <rex.raphael@outlook.com>
 #  - Thomas Stockx <thomas@stockxit.com>