Pigeon Examples

HostApi Example

This example gives an overview of how to use Pigeon to call into the host-platform from Flutter.

For instructions to set up your own Pigeon usage see these steps.

message.dart

This is the Pigeon file that describes the interface that will be used to call from Flutter to the host-platform.

import 'package:pigeon/pigeon.dart';

class Book {
  String? title;
  String? author;
}

@HostApi()
abstract class BookApi {
  List<Book?> search(String keyword);
}

invocation

This an example call to Pigeon that would ingest a defintion file pigeons/message.dart and generate corresponding output code for each supported language. (In actual use, you would not normally use both Objective-C and Swift, or both Java and Kotlin, but instead use just the languages matching your project.)

flutter pub run pigeon \
  --input pigeons/message.dart \
  --dart_out lib/pigeon.dart \
  --objc_header_out ios/Runner/pigeon.h \
  --objc_source_out ios/Runner/pigeon.m \
  --swift_out ios/Runner/Pigeon.swift \
  --kotlin_out android/app/src/main/kotlin/dev/flutter/pigeon/Pigeon.kt \
  --kotlin_package "dev.flutter.pigeon" \
  --java_out android/app/src/main/java/dev/flutter/pigeon/Pigeon.java \
  --java_package "dev.flutter.pigeon" \
  --cpp_header_out windows/runner/pigeon.h \
  --cpp_source_out windows/runner/pigeon.cpp \
  --cpp_namespace pigeon

AppDelegate.m

This is the code that will use the generated Objective-C code to receive calls from Flutter.

#import "AppDelegate.h"
#import <Flutter/Flutter.h>
#import "pigeon.h"

@interface MyApi : NSObject <BookApi>
@end

@implementation MyApi
-(NSArray<Book *> *)searchKeyword:(NSString *)keyword error:(FlutterError **)error {
  Book *result = [[Book alloc] init];
  result.title =
      [NSString stringWithFormat:@"%@'s Life", request.query];
  result.author = keyword;
  return @[ result ];
}
@end

@implementation AppDelegate
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary<UIApplicationLaunchOptionsKey, id> *)launchOptions {
  MyApi *api = [[MyApi alloc] init];
  BookApiSetup(getFlutterEngine().binaryMessenger, api);
  return YES;
}
@end

AppDelegate.swift

This is the code that will use the generated Swift code to receive calls from Flutter.

import Flutter

class MyApi: NSObject, BookApi {
  func search(keyword: String) -> [Book] {
    let result = Book(title: "\(keyword)'s Life", author: keyword)
    return [result]
  }
}

class AppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?
  ) -> Bool {
    let api = MyApi()
    BookApiSetup.setUp(getFlutterEngine().binaryMessenger, api)
    return true
  }
}

StartActivity.java

This is the code that will use the generated Java code to receive calls from Flutter.

import dev.flutter.pigeon.Pigeon.*;
import java.util.Collections;

public class StartActivity extends Activity {
  private class MyApi implements BookApi {
    List<Book> search(String keyword) {
      Book result = new Book();
      result.author = keyword;
      result.title = String.format("%s's Life", keyword);
      return Collections.singletonList(result)
    }
  }

  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    BookApi.setup(getBinaryMessenger(), new MyApi());
  }
}

test.dart

This is the Dart code that will call into the host-platform using the generated Dart code.

import 'pigeon.dart';

void main() {
  testWidgets("test pigeon", (WidgetTester tester) async {
    Api api = Api();
    List<Book?> reply = await api.search("Aaron");
    expect(reply[0].title, equals("Aaron's Life"));
  });
}

Swift / Kotlin Plugin Example

A downloadable example of using Pigeon to create a Flutter Plugin with Swift and Kotlin can be found at gaaclarke/flutter_plugin_example.

Swift / Kotlin Add-to-app Example

A full example of using Pigeon for add-to-app with Swift on iOS can be found at samples/add_to_app/books.

Video player plugin

A full real-world example can also be found in the video_player plugin.