🔌 Native Channels in Flutter — A Complete Guide

This content originally appeared on DEV Community and was authored by Omar Elsadany

When building Flutter apps, sometimes Dart alone isn’t enough. You may need native functionality—like accessing sensors, battery info, Bluetooth, or a custom SDK.

That’s where Platform Channels (a.k.a. Native Channels) come in. They allow Flutter to communicate with the host platform (Android/iOS, desktop, etc.) and execute native code seamlessly.

What Are Platform Channels?

Flutter runs on its own engine with Dart, but you can bridge to the host platform when needed.

Platform channels send asynchronous messages between:

• Flutter (Dart side)
• Host platform (Kotlin/Java for Android, Swift/Objective-C for iOS, etc.)

Think of it as a two-way communication bridge.

Types of Platform Channels

Flutter provides three types of channels:

1. MethodChannel

Best for one-time operations.

• Purpose: Invoke a native method and get a response back.
• Pattern: Request → Response (like a function call).

Use Cases:

• Fetching device info (battery, OS version, etc.)
• Triggering a single action (open camera, share a file)

2. EventChannel

Best for continuous streams of data.

• Purpose: Subscribe once and keep receiving updates.
• Pattern: Stream of events over time.

Use Cases:

• Sensors (accelerometer, gyroscope, pedometer)
• System updates (battery state, connectivity changes)

3. BasicMessageChannel

Best for flexible, bi-directional messaging.

• Purpose: Send raw, asynchronous messages (text, JSON, binary) back and forth.
• Pattern: Free-form communication (no fixed method names).

Use Cases:

• Continuous two-way messaging
• Custom protocols (status updates, commands)

Platforms & Native Languages

Flutter supports multiple platforms and integrates with their native languages:

• Android → Kotlin, Java
• iOS → Swift, Objective-C
• Windows → C++
• macOS → Objective-C
• Linux → C

Code Examples

Example 1: Get Battery Level (MethodChannel)

Use case: Flutter asks Android for current battery percentage.

// Flutter side
static const platform = MethodChannel('battery');

Future<void> getBatteryLevel() async {
  final int level = await platform.invokeMethod('getBatteryLevel');
  print("Battery level: $level%");
}

// Android side (Kotlin)
MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "battery")
  .setMethodCallHandler { call, result ->
    if (call.method == "getBatteryLevel") {
      val batteryLevel = getBatteryPercentage()
      result.success(batteryLevel)
    }
  }

Example 2: Steps Counter (EventChannel)

Use case: Count user steps while moving.

• EventChannel → Stream real-time step counts.

// Flutter side
static const eventChannel = EventChannel('stepCountStream');

void listenSteps() {
  eventChannel.receiveBroadcastStream().listen((event) {
    print("Steps: $event");
  }, onError: (error) {
    print("Error: $error");
  });
}

// Android side (Kotlin)
EventChannel(flutterEngine.dartExecutor.binaryMessenger, "stepCountStream")
  .setStreamHandler(object : EventChannel.StreamHandler {
    override fun onListen(arguments: Any?, events: EventChannel.EventSink) {
        // Example: simulate step counter
        events.success(100) // Replace with real step counter data
    }

    override fun onCancel(arguments: Any?) {
        // Stop sending events when cancelled
    }
  })

Example 3: Live Chat / Messaging (BasicMessageChannel)

Use case: Exchange chat messages between Flutter UI and a native chat engine.

static const messageChannel =
    BasicMessageChannel<String>('chat', StringCodec());

void sendMessage(String msg) {
  messageChannel.send(msg);
}

void listenMessages() {
  messageChannel.setMessageHandler((msg) async {
    print("New message: $msg");
  });
}

Final Thoughts

• MethodChannel → One-time calls.
• EventChannel → Continuous updates.
• BasicMessageChannel → Free-form, two-way messaging.

GitHub Projects

Repository: https://github.com/AhmedTarek-f/native-channel-app.git

Complete Flutter app demonstrating all three platform channel types:

Battery Level (MethodChannel)

• Get device battery percentage on button tap
• Simple request → response pattern

Live Chat (BasicMessageChannel)

• Real-time bidirectional messaging
• Send and receive messages between Flutter and native

Step Counter (MethodChannel + EventChannel)

• MethodChannel: Start/stop step counting service
• EventChannel: Stream real-time step updates
• Background service with sensor integration

Quick Start

git clone https://github.com/AhmedTarek-f/native-channel-app.git
cd native-channel-app
flutter pub get
flutter run

Features: All 3 channel types • Foreground services • Sensor integration • Permission handling • BLoC state management

This content originally appeared on DEV Community and was authored by Omar Elsadany