Flutter To Host Example

A Flutter project demonstrating bidirectional communication between Flutter and native platforms (iOS, Android, macOS) using Pigeon.

Overview

This project showcases how to implement type-safe communication between Flutter and native code using the Pigeon package. It demonstrates:

• Flutter-to-native platform communication
• Native-to-Flutter communication
• Handling of complex data types
• Integration with Stacked architecture

What is Pigeon?

Pigeon is a code generator tool that creates type-safe interfaces for communication between Flutter and host platforms. It generates code for:

• Dart (Flutter)
• Swift/Objective-C (iOS/macOS)
• Kotlin/Java (Android)
• C++ (Windows/Linux)

This eliminates the need for error-prone manual coding of platform channels and ensures type safety across language boundaries.

Project Structure

• /pigeons/example_pigeons.dart - Pigeon interface definitions
• /lib/src/messages.g.dart - Generated Dart code for Pigeon interfaces
• iOS, Android, and macOS folders contain the generated native code

Key Features

1. Type-Safe APIs

The project defines two main APIs:

// Flutter to Host
@HostApi()
abstract class ExampleHostApi {
  String getHostLanguage();
  int add(int a, int b);
  bool sendMessage(MessageData message);
}

// Host to Flutter
@FlutterApi()
abstract class MessageFlutterApi {
  String flutterMethod(String? aString);
}

2. Complex Data Types

Demonstrates passing complex data structures between Flutter and native platforms:

class MessageData {
  MessageData({required this.code, required this.data});
  String? name;
  String? description;
  Code code;
  Map<String?, String?> data;
}

3. Bidirectional Communication

• Flutter can call native methods via ExampleHostApi
• Native platforms can call Flutter methods via MessageFlutterApi

Getting Started

Prerequisites

• Flutter SDK
• Dart SDK
• Xcode (for iOS/macOS)
• Android Studio (for Android)

Setup

1. Clone the repository
2. Install dependencies:

   flutter pub get
   

3. Run the code generation for Pigeon:

   dart run pigeon --input pigeons/example_pigeons.dart
   

4. Run the app:

   flutter run
   

How It Works

1. Define your API interfaces in the Pigeon file (pigeons/example_pigeons.dart)
2. Run the Pigeon code generator to create platform-specific code
3. Implement the native side of the API in Swift, Kotlin, etc.
4. Use the generated Dart classes in your Flutter code

Implementation Notes

Flutter Side

The app uses the Stacked architecture pattern for state management. The HomeViewModel demonstrates calling native methods through the Pigeon-generated API:

void showBottomSheet() {
  MessageData messageData = MessageData(
    code: Code.one,
    data: {'name': 'From flutter', 'description': 'because its cool!'},
  );
  _exampleHostApi.sendMessage(messageData);
  // ...
}

Native Side

Native platforms implement the interface defined by Pigeon. For example, iOS implements the ExampleHostApi protocol in Swift.

Modifying the API

To modify or extend the API:

1. Edit the pigeons/example_pigeons.dart file
2. Run the Pigeon code generator:

   dart run pigeon --input pigeons/example_pigeons.dart
   

3. Implement any new methods on the native side
4. Use the updated API in your Flutter code

Resources

• Pigeon Package
• Flutter Platform Channels
• Stacked Architecture

License

This project is for educational purposes and is available under the MIT License.