[platform_channels] adds implementation of BasicMessageChannel for iOS (#610)

platform_channels/README.md

@@ -2,8 +2,6 @@
 
 A sample app which demonstrates how to use `MethodChannel`, `EventChannel`, `BasicMessageChannel` and `MessageCodec` in Flutter.
 
-This sample is currently being built. Not all platforms and functionality are in place.
-
 ## Goals
 
 * Demonstrate how to use `MethodChannel` to invoke platform methods.

platform_channels/ios/Runner/AppDelegate.swift

@@ -45,7 +45,45 @@ import Flutter
         
         FlutterEventChannel(name: "eventChannelDemo", binaryMessenger: flutterViewController.binaryMessenger).setStreamHandler(AccelerometerStreamHandler())
         
+        var petList : [[String:String]] = []
+        
+        // A FlutterBasicMessageChannel for sending petList to Dart.
+        let stringCodecChannel = FlutterBasicMessageChannel(name: "stringCodecDemo", binaryMessenger: flutterViewController.binaryMessenger, codec: FlutterStringCodec.sharedInstance())
+        
+        // Registers a MessageHandler for FlutterBasicMessageChannel to receive pet details.
+        FlutterBasicMessageChannel(name: "jsonMessageCodecDemo", binaryMessenger: flutterViewController.binaryMessenger, codec: FlutterJSONMessageCodec.sharedInstance())
+            .setMessageHandler{(message: Any?, reply: FlutterReply) -> Void in
+                petList.insert(message! as! [String: String], at: 0)
+                stringCodecChannel.sendMessage(self.convertPetListToJson(petList: petList))
+            }
+        
+        // Registers a MessageHandler for FlutterBasicMessageHandler to receive indices of detail records to remove from the petList.
+        FlutterBasicMessageChannel(name: "binaryCodecDemo", binaryMessenger: flutterViewController.binaryMessenger, codec: FlutterBinaryCodec.sharedInstance()).setMessageHandler{
+            (message: Any?, reply: FlutterReply) -> Void in
+            
+            guard let index = Int.init(String.init(data: message! as! Data, encoding: String.Encoding.utf8)!) else {
+                reply(nil)
+                return
+            }
+            
+            if (index >= 0 && index < petList.count) {
+                petList.remove(at: index)
+                reply("Removed Successfully".data(using: .utf8)!)
+                stringCodecChannel.sendMessage(self.convertPetListToJson(petList: petList))
+            } else {
+                reply(nil)
+            }
+        }
+        
         GeneratedPluginRegistrant.register(with: self)
         return super.application(application, didFinishLaunchingWithOptions: launchOptions)
     }
+    
+    // Function to convert petList to json string.
+    func convertPetListToJson(petList: [[String: String]]) -> String? {
+        guard let data = try? JSONSerialization.data(withJSONObject: ["petList": petList], options: .prettyPrinted) else {
+            return nil
+        }
+        return String(data: data, encoding: String.Encoding.utf8)
+    }
 }

platform_channels/lib/main.dart

@@ -25,6 +25,11 @@ class PlatformChannelSample extends StatelessWidget {
         '/addPetDetails': (context) => AddPetDetails(),
       },
       title: 'Platform Channel Sample',
+      theme: ThemeData(
+        snackBarTheme: SnackBarThemeData(
+          backgroundColor: Colors.blue[500],
+        ),
+      ),
       home: HomePage(),
     );
   }

platform_channels/lib/src/pet_list_screen.dart

@@ -15,6 +15,7 @@ class PetListScreen extends StatefulWidget {
 
 class _PetListScreenState extends State<PetListScreen> {
   PetListModel petListModel;
+  final scaffoldKey = GlobalKey<ScaffoldState>();
 
   @override
   void initState() {
@@ -23,9 +24,17 @@ class _PetListScreenState extends State<PetListScreen> {
     // to PetModel.
     BasicMessageChannel('stringCodecDemo', StringCodec())
         .setMessageHandler((message) async {
-      setState(() {
-        petListModel = PetListModel.fromJson(message);
-      });
+      if (message == null) {
+        scaffoldKey.currentState.showSnackBar(
+          SnackBar(
+              content:
+                  const Text('An error occurred while adding pet details.')),
+        );
+      } else {
+        setState(() {
+          petListModel = PetListModel.fromJson(message);
+        });
+      }
       return;
     });
   }
@@ -33,6 +42,7 @@ class _PetListScreenState extends State<PetListScreen> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
+      key: scaffoldKey,
       appBar: AppBar(
         title: Text('Pet List'),
       ),
@@ -84,7 +94,6 @@ class BuildPetList extends StatelessWidget {
 
   void showSnackBar(String message, BuildContext context) {
     Scaffold.of(context).showSnackBar(SnackBar(
-      backgroundColor: Theme.of(context).primaryColor,
       content: Text(message),
     ));
   }