Event Channel & Method Channel in Flutter

In Flutter, the MethodChannel and EventChannel classes are used for communication between Dart code and platform-specific code (written in Java, Kotlin, Objective-C, or Swift).

Here’s an overview of the differences between MethodChannel and EventChannel:
1. MethodChannel: MethodChannel is used for invoking platform-specific methods from Dart and receiving the results back. It enables bi-directional communication where Dart code can call methods in platform-specific code and receive the results asynchronously.

• Dart-to-Platform: In Dart, you use the invokeMethod method on the MethodChannel to call a platform-specific method. On the platform side, you handle the method invocation and return the result asynchronously.
• Platform-to-Dart: After the platform-specific method completes execution, it can use the Result object to send a result or error back to the Dart side.

// In Dart code
final platformChannel = MethodChannel('channel_name');
final result = await platformChannel.invokeMethod('method_name', arguments);

// In Platform-specific code (Java/Kotlin or Objective-C/Swift)
methodChannel.setMethodCallHandler { call, result ->
    if (call.method == "method_name") {
        // Handle the method call and send the result back asynchronously
        result.success(responseData); // or result.error(errorCode, errorMessage, errorDetails)
    }
};

2. EventChannel: EventChannel is used for receiving continuous streams of events or data from platform-specific code. It enables the platform-specific code to send streams of data or events to the Dart side.

• Platform-to-Dart: On the platform side, you set up a stream of events or data and send them using the EventSink.
• Dart-to-Platform: In Dart, you listen to the stream provided by the EventChannel to receive the events or data sent from the platform.

// In Dart code
final eventChannel = EventChannel('channel_name');
final eventStream = eventChannel.receiveBroadcastStream();

eventStream.listen((event) {
    // Handle events or data received from the platform
});

// In Platform-specific code (Java/Kotlin or Objective-C/Swift)
eventChannel.setStreamHandler(object : StreamHandler {
    override fun onListen(arguments: Any?, eventSink: EventSink) {
        // Set up the stream and send events or data through the eventSink
    }

    override fun onCancel(arguments: Any?) {
        // Clean up resources when the stream is canceled by Dart
    }
})

In summary, MethodChannel is used for invoking platform-specific methods and receiving results asynchronously, while EventChannel is used for receiving continuous streams of events or data from the platform. Both channels facilitate communication between Dart and platform-specific code in Flutter applications.