MethodChannel registration

Flutter course
Expert
Lesson 17/39
4 min

MethodChannel registration

A plugin starts on the Dart side with a registerWith method. It creates a MethodChannel and captures incoming native calls with setMethodCallHandler. The plugin is registered automatically when the app launches.

class MyPlugin {
  static const _channel = MethodChannel('my_plugin');

  static void registerWith() {
    _channel.setMethodCallHandler(_handle);
  }

  static Future<dynamic> _handle(MethodCall call) async {
    return 'ok';
  }
}

setMethodCallHandler

setMethodCallHandler catches incoming MethodCall messages from native. The handler branches on the call's method name and returns a result. This is the plugin's Dart-native bridge.

Practice Define a plugin with registerWith

Define MyPlugin: static const _channel = MethodChannel('my_plugin'), a static void registerWith() method that calls _channel.setMethodCallHandler(_handle), and a static Future<dynamic> _handle(MethodCall call) async => 'ok'. In main, print 'kaydedildi'.

Starter code

main.dart

import 'package:flutter/services.dart';

// MyPlugin sınıfını tanımla
// 'my_plugin' adlı bir MethodChannel static const ata
// kayıt metodu handler ataması yapsın
// çağrı işleyici metodu 'ok' döndürsün

void main() {
  // 'kaydedildi' yazdır
}

Sample solution

main.dart

import 'package:flutter/services.dart';

class MyPlugin {
  static const _channel = MethodChannel('my_plugin');

  static void registerWith() {
    _channel.setMethodCallHandler(_handle);
  }

  static Future<dynamic> _handle(MethodCall call) async => 'ok';
}

void main() {
  print('kaydedildi');
}

Expected output

kaydedildi

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What does the registerWith method do?

Opens a database
Starts the app
Draws the widget tree
Creates a MethodChannel and registers a call listener Correct answer

Explanation: registerWith sets up the MethodChannel and assigns the handler that listens to incoming native calls via setMethodCallHandler.

2 setMethodCallHandler call

Question

_channel.____(_handle);

Answer

_channel.setMethodCallHandler(_handle);

Explanation: setMethodCallHandler assigns the handler that catches MethodCalls; invokeMethod calls from Dart to native, setMessageHandler is lower-level, and listen is for streams.

3 MethodChannel registration matches

Term	Meaning
`registerWith`	Plugin registration
`MethodChannel`	Call channel
`plugin`	Native-bridged package
`setMethodCallHandler`	Call listener

import 'package:flutter/services.dart'; class MyPlugin { static const _channel = MethodChannel('my_plugin'); static void registerWith() { _channel.setMethodCallHandler(_handle); } static Future<dynamic> _handle(MethodCall call) async => 'ok'; } void main() { print('kaydedildi'); }

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MethodChannel registration