# Platform Channels, Plugins and Permissions — Flutter

Source: https://www.skillbyai.com/en/flutter/d-platform

> Reaching native APIs.

## Talking to Kotlin, Swift and friends

Most native features (camera, location, sensors, payments) are already wrapped by **plugins** on pub.dev; check platform support, maintenance and the "Flutter Favorite" or verified publisher badges before adopting one. When nothing fits, a **platform channel** sends asynchronous messages between Dart and native code: a `MethodChannel` on the Dart side calls `invokeMethod`, and Kotlin or Swift code registered on the same channel name handles it and returns a result or error (surfaced as `PlatformException`). **Pigeon** generates type-safe channel code from a Dart interface, and **dart:ffi** calls C libraries directly. Runtime **permissions** are typically requested with the `permission_handler` package, but you must also declare them in `AndroidManifest.xml` and add usage descriptions to iOS `Info.plist`.

## Calling native code over a MethodChannel

Dart side; Kotlin/Swift register a handler for the same name.

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

class Battery {
  static const _channel = MethodChannel('com.example.app/battery');

  Future<int?> level() async {
    try {
      return await _channel.invokeMethod<int>('getBatteryLevel');
    } on PlatformException catch (e) {
      debugPrint('Battery unavailable: ${e.message}');
      return null;
    }
  }
}

// permission_handler (check the docs for your version)
// final status = await Permission.camera.request();
// if (status.isGranted) { openCamera(); }
```

## Explain before you ask

Show your own screen explaining why a permission is needed before the system prompt, and handle the "permanently denied" case by offering a link to app settings.

**Quiz:** What Dart class sends method calls to native Android or iOS code?

- [ ] FutureBuilder
- [x] MethodChannel
- [ ] InheritedWidget
- [ ] GoRouter

*Answer:* MethodChannel. Native code registers a handler on the same channel name.