Add creation parameters to UiKitView. (#23800)

packages/flutter/lib/src/widgets/platform_view.dart

@@ -56,8 +56,8 @@ class AndroidView extends StatefulWidget {
   ///
   /// {@template flutter.widgets.platformViews.constructorParams}
   /// The `viewType` and `hitTestBehavior` parameters must not be null.
-  /// {@endtemplate}
   /// If `creationParams` is not null then `creationParamsCodec` must not be null.
+  /// {@endtemplate}
   AndroidView({ // ignore: prefer_const_constructors_in_immutables
                 // TODO(aam): Remove lint ignore above once https://dartbug.com/34297 is fixed
     Key key,
@@ -193,8 +193,11 @@ class UiKitView extends StatefulWidget {
     this.onPlatformViewCreated,
     this.hitTestBehavior = PlatformViewHitTestBehavior.opaque,
     this.layoutDirection,
+    this.creationParams,
+    this.creationParamsCodec,
   }) : assert(viewType != null),
         assert(hitTestBehavior != null),
+        assert(creationParams == null || creationParamsCodec != null),
         super(key: key);
 
   // TODO(amirh): reference the iOS API doc once avaliable.
@@ -212,6 +215,19 @@ class UiKitView extends StatefulWidget {
   /// {@macro flutter.widgets.platformViews.directionParam}
   final TextDirection layoutDirection;
 
+  /// Passed as the `arguments` argument of [-[FlutterPlatformViewFactory createWithFrame:viewIdentifier:arguments:]](/objcdoc/Protocols/FlutterPlatformViewFactory.html#/c:objc(pl)FlutterPlatformViewFactory(im)createWithFrame:viewIdentifier:arguments:)
+  ///
+  /// This can be used by plugins to pass constructor parameters to the embedded Android view.
+  final dynamic creationParams;
+
+  /// The codec used to encode `creationParams` before sending it to the
+  /// platform side. It should match the codec returned by [-[FlutterPlatformViewFactory createArgsCodec:]](/objcdoc/Protocols/FlutterPlatformViewFactory.html#/c:objc(pl)FlutterPlatformViewFactory(im)createArgsCodec)
+  ///
+  /// This is typically one of: [StandardMessageCodec], [JSONMessageCodec], [StringCodec], or [BinaryCodec].
+  ///
+  /// This must not be null if [creationParams] is not null.
+  final MessageCodec<dynamic> creationParamsCodec;
+
   @override
   State<UiKitView> createState() => _UiKitViewState();
 }
@@ -379,6 +395,8 @@ class _UiKitViewState extends State<UiKitView> {
       id: _id,
       viewType: widget.viewType,
       layoutDirection: _layoutDirection,
+      creationParams: widget.creationParams,
+      creationParamsCodec: widget.creationParamsCodec,
     );
     if (!mounted) {
       controller.dispose();

packages/flutter/test/services/fake_platform_views.dart

@@ -179,6 +179,7 @@ class FakeIosPlatformViewsController {
     final Map<dynamic, dynamic> args = call.arguments;
     final int id = args['id'];
     final String viewType = args['viewType'];
+    final Uint8List creationParams = args['params'];
 
     if (_views.containsKey(id)) {
       throw PlatformException(
@@ -194,7 +195,7 @@ class FakeIosPlatformViewsController {
       );
     }
 
-    _views[id] = FakeUiKitView(id, viewType);
+    _views[id] = FakeUiKitView(id, viewType, creationParams);
     return Future<int>.sync(() => null);
   }
 
@@ -272,10 +273,11 @@ class FakeAndroidMotionEvent {
 }
 
 class FakeUiKitView {
-  FakeUiKitView(this.id, this.type);
+  FakeUiKitView(this.id, this.type, [this.creationParams]);
 
   final int id;
   final String type;
+  final Uint8List creationParams;
 
   @override
   bool operator ==(dynamic other) {
@@ -283,7 +285,8 @@ class FakeUiKitView {
       return false;
     final FakeUiKitView typedOther = other;
     return id == typedOther.id &&
-      type == typedOther.type;
+           type == typedOther.type &&
+           creationParams == typedOther.creationParams;
   }
 
   @override
@@ -291,6 +294,6 @@ class FakeUiKitView {
 
   @override
   String toString() {
-    return 'FakeIosPlatformView(id: $id, type: $type)';
+    return 'FakeUiKitView(id: $id, type: $type, creationParams: $creationParams)';
   }
 }

packages/flutter/test/widgets/platform_view_test.dart

@@ -961,5 +961,43 @@ void main() {
       );
     });
 
+    testWidgets('Create UIView with params', (WidgetTester tester) async {
+      final int currentViewId = platformViewsRegistry.getNextPlatformViewId();
+      final FakeIosPlatformViewsController viewsController = FakeIosPlatformViewsController();
+      viewsController.registerViewType('webview');
+
+      await tester.pumpWidget(
+        Center(
+          child: SizedBox(
+            width: 200.0,
+            height: 100.0,
+            child: UiKitView(
+              viewType: 'webview',
+              layoutDirection: TextDirection.ltr,
+              creationParams: 'creation parameters',
+              creationParamsCodec: const StringCodec(),
+            ),
+          ),
+        ),
+      );
+
+      final FakeUiKitView fakeView = viewsController.views.first;
+      final Uint8List rawCreationParams = fakeView.creationParams;
+      final ByteData byteData = ByteData.view(
+          rawCreationParams.buffer,
+          rawCreationParams.offsetInBytes,
+          rawCreationParams.lengthInBytes
+      );
+      final dynamic actualParams = const StringCodec().decodeMessage(byteData);
+
+      expect(actualParams, 'creation parameters');
+      expect(
+        viewsController.views,
+        unorderedEquals(<FakeUiKitView>[
+          FakeUiKitView(currentViewId + 1, 'webview', fakeView.creationParams)
+        ]),
+      );
+    });
+
   });
 }