How to send command and command notification messages in Flutter SDK (RCIMIWMessageType.command and RCIMIWMessageType.commandNotification)

Technical guides
1

Description

Starting with Flutter 5.4.0, you can’t create or send RCIMIWCommandMessage (command message) and RCIMIWCommandNotificationMessage (command notification message) types.

Analysis

The Flutter SDK doesn’t currently provide a create method for command messages (RCIMIWCommandMessage) and command notification messages (RCIMIWCommandNotificationMessage). To send these messages from the client, you’ll need to define a wrapper class in the Flutter layer. This approach is supported only in version 5.4.0 and above.

Follow the steps below for implementation.

Solution

Create a command message

  1. Define the message in the Flutter layer by creating wrapper_command_message.dart.

    import 'package:rongcloud_im_wrapper_plugin/rongcloud_im_wrapper_plugin.dart';
import 'dart:convert' as json_lib show json;

// Custom messages must extend RCIMIWUserCustomMessage
class RCIMDCommandMessage extends RCIMIWUserCustomMessage {
  String? name;
  String? data;
  // 1. Define your constructor, calling the parent class RCIMIWUserCustomMessage(RCIMIWConversationType type, String targetId)
  RCIMDCommandMessage(RCIMIWConversationType type, String targetId, this.name, this.data) : super(type, targetId);

  // 2. Inherit the parent class constructor
  RCIMDCommandMessage.fromJson(Map<String, dynamic> json) : super.fromJson(json);

  // 3. Implement the parent class's decode/encode/messageObjectName
  @override
  void decode(String jsonStr) {
    Map map = json_lib.json.decode(jsonStr.toString());
    // The key must match the one passed from the native layer
    name = map['name'];
    name = map['data'];
  }

  @override
  String encode() {
    Map map = {};
    // The key must match the one passed to the native layer
    map['name'] = name;
    map['data'] = data;
    return json_lib.json.encode(map);
  }

  @override
  String messageObjectName() {
    return "RC:CmdMsg";
  }

  // 4. Implement the parent class's toJson
  @override
  Map<String, dynamic> toJson() {
    final Map<String, dynamic> json = super.toJson();
    // 'content' must not be modified
    json['content'] = encode();
    return json;
  }
}

  2. Register the message in the native layer.

    iOS: xxxx/ios/Runner/AppDelegate.m

    - (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [GeneratedPluginRegistrant registerWithRegistry:self];
    NSMutableArray *marr = [NSMutableArray arrayWithObjects:[RCDPokeMessage class], [RCCommandMessage class], nil];
    [RCIMWrapperEngine sharedInstance].messageContentClassList = marr.copy;
    ...
}

    Android: example/android/app/src/main/java/cn/rongcloud/im/wrapper/flutter/example/MainActivity.java

    public class MainActivity extends FlutterActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        List<Class<? extends MessageContent>> list = new ArrayList<>();
        list.add(PokeMessage.class);
        list.add(CommandMessage.class);
        RCIMWrapperEngine.getInstance().messageContentClassList = list;

    }
}
Send a command message
  RCIMDCommandMessage msg = RCIMDCommandMessage(type, targetId, "name", "data");
  _sendMessage(msg, useCallback);

Both received and successfully sent messages will be processed as RCIMIWCommandMessage. For other use cases like receiving messages, simply handle RCIMIWCommandMessage.

If you have any questions, feel free to submit a ticket.