Flutter platform channel

Yogendra singh

28 April 2023

Flutter platform channel

Flutter provides a flexible system to access platform-specific features of Android or IOS.
We can access platform-specific functionality like device information, sensors, battery, device camera, battery level, open browser, etc using flutter platform channels.

Read more about Flutter app development from mobikul.

How does it Work?

Flutter dart code sends messages to its host(Android or IOS) over a platform channel.
Host(Android or IOS) listens on the platform channel and receives the message. It then calls into any number of platform-specific APIs—using the native programming language—and sends a response back to the client (Flutter dart code).

Step 1: Android platform-specific implementation

package com.example.flutter_app

import android.util.Log
import androidx.annotation.NonNull
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel

class MainActivity : FlutterActivity() {
    private val CHANNEL = "com.example.flutter/device_info" // Unique Channel
    
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)

        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler {
            // Note: this method is invoked on the main thread.
            call, result ->
            if (call.method == "getDeviceInfo") {
                val deviceInfo: HashMap<String, String> = getDeviceInfo()
                if (deviceInfo.isNotEmpty()) {
                    result.success(deviceInfo)
                } else {
                    result.error("UNAVAILABLE", "Device info not available.", null)
                }
            } else {
                result.notImplemented()
            }

        }
    }

    private fun getDeviceInfo(): HashMap<String, String> {
        val deviceInfo = HashMap<String, String>()
        deviceInfo["version"] = System.getProperty("os.version").toString() // OS version
        deviceInfo["device"] = android.os.Build.DEVICE           // Device
        deviceInfo["model"] = android.os.Build.MODEL            // Model
        deviceInfo["product"] = android.os.Build.PRODUCT          // Product
        return deviceInfo
    }
}

package com.example.flutter_app

import android.util.Log

import androidx.annotation.NonNull

import io.flutter.embedding.android.FlutterActivity

import io.flutter.embedding.engine.FlutterEngine

import io.flutter.plugin.common.MethodChannel

class MainActivity : FlutterActivity() {

private val CHANNEL = "com.example.flutter/device_info" // Unique Channel

override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {

super.configureFlutterEngine(flutterEngine)

MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler {

// Note: this method is invoked on the main thread.

call, result ->

if (call.method == "getDeviceInfo") {

val deviceInfo: HashMap<String, String> = getDeviceInfo()

if (deviceInfo.isNotEmpty()) {

result.success(deviceInfo)

} else {

result.error("UNAVAILABLE", "Device info not available.", null)

}

} else {

result.notImplemented()

}

private fun getDeviceInfo(): HashMap<String, String> {

val deviceInfo = HashMap<String, String>()

deviceInfo["version"] = System.getProperty("os.version").toString() // OS version

deviceInfo["device"] = android.os.Build.DEVICE // Device

deviceInfo["model"] = android.os.Build.MODEL // Model

deviceInfo["product"] = android.os.Build.PRODUCT // Product

return deviceInfo

}

Step 2: Flutter platform-specific implementation

Let’s declare platform Channel

  static const platform =
      const MethodChannel('com.example.flutter/device_info');

1 2	static const platform = const MethodChannel('com.example.flutter/device_info');

Invoke function by passing the function name and arguments.

  Future<void> _getDeviceInfo() async {
    String result;
    try {
      platform.invokeMethod('getDeviceInfo',"Pass your payload supported by StandardMethodCodec").then((value) {
        result = value.toString();
        setState(() {
          deviceInfo = result;
        });
      });
    } on PlatformException catch (e) {
      print("_getDeviceInfo==>${e.message}");
    }
  }

Future<void> _getDeviceInfo() async {

String result;

try {

platform.invokeMethod('getDeviceInfo',"Pass your payload supported by StandardMethodCodec").then((value) {

result = value.toString();

setState(() {

deviceInfo = result;

});

} on PlatformException catch (e) {

print("_getDeviceInfo==>${e.message}");

}

Let’s Review Complete Flutter code

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const platform =
      const MethodChannel('com.example.flutter/device_info');
  String deviceInfo = "";

  @override
  void initState() {
    _getDeviceInfo();
    super.initState();
  }

  Future<void> _getDeviceInfo() async {
    String result;
    try {
      platform.invokeMethod('getDeviceInfo').then((value) {
        result = value.toString();
        setState(() {
          deviceInfo = result;
        });
      });
    } on PlatformException catch (e) {
      print("_getDeviceInfo==>${e.message}");
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(child: Text(deviceInfo)),
    );
  }
}

import 'package:flutter/material.dart';

import 'package:flutter/services.dart';

void main() {

runApp(MyApp());

}

class MyApp extends StatelessWidget {

// This widget is the root of your application.

@override

Widget build(BuildContext context) {

return MaterialApp(

title: 'Flutter Demo',

theme: ThemeData(

primarySwatch: Colors.blue,

visualDensity: VisualDensity.adaptivePlatformDensity,

home: MyHomePage(title: 'Flutter Demo Home Page'),

);

}

class MyHomePage extends StatefulWidget {

MyHomePage({Key key, this.title}) : super(key: key);

final String title;

@override

_MyHomePageState createState() => _MyHomePageState();

}

class _MyHomePageState extends State<MyHomePage> {

static const platform =

const MethodChannel('com.example.flutter/device_info');

String deviceInfo = "";

@override

void initState() {

_getDeviceInfo();

super.initState();

}

Future<void> _getDeviceInfo() async {

String result;

try {

platform.invokeMethod('getDeviceInfo').then((value) {

result = value.toString();

setState(() {

deviceInfo = result;

});

} on PlatformException catch (e) {

print("_getDeviceInfo==>${e.message}");

}

@override

Widget build(BuildContext context) {

return Scaffold(

appBar: AppBar(

title: Text(widget.title),

body: Center(child: Text(deviceInfo)),

);

}

I hope this blog will help to access the platform-specific APIs and features.

Happy Learning 🙂

Reference Links :

https://flutter.dev/docs/development/platform-integration/platform-channels