fl_channel

pub package Web example

Native channel communication for Flutter. Create event channels, control their lifecycle from Dart, and push events from native code back to Flutter.

Supported platforms

Platform Support Native implementation
Android Yes Kotlin, minSdk 24
iOS Yes Swift, iOS 15.0+, Swift Package Manager and CocoaPods
macOS Yes Swift, macOS 12.0+, Swift Package Manager and CocoaPods
Windows Yes C++, MethodChannel and EventChannel
Linux Yes C++ and GTK, MethodChannel and EventChannel
Web Yes Dart event stream and JavaScript bridge
HarmonyOS (OHOS) Yes ArkTS

Requirements

  • Flutter >=3.24.0
  • Dart >=3.5.0

Android builds use AGP 9.1 and Gradle 9.3, so they require Flutter 3.47.0 or later. HarmonyOS builds use the OpenHarmony Flutter SDK, which may be based on an earlier Flutter release.

Installation

dependencies:
  fl_channel: ^2.0.0

Usage

Create an event channel

final FlEventChannel? channel = await FlChannel.instance.create('event_test');

create returns the existing channel when it has already been created.

Listen to events

final bool listening = channel?.listen(
  (dynamic data) {
    debugPrint('received: $data');
  },
  onError: (dynamic error) {
    debugPrint('error: $error');
  },
) ?? false;

Pause, resume and dispose

channel?.pause();
channel?.resume();
final bool paused = channel?.isPaused ?? false;

await channel?.dispose();

Send an event from Dart for demonstration

await FlChannel.instance.sendEventFromNative('event_test', 'Hello from Dart');

This method goes through the native plugin and emits the payload on the event channel. On Web it dispatches the payload to the local Dart event stream. It is useful for smoke tests; real applications usually send events from native code as shown below.

Default channel

final FlEventChannel? channel = await FlChannel.instance.defaultEventChannel();
await FlChannel.instance.defaultDispose();

The default channel name is fl_channel/event.

Pure Dart data stream

FlDataStream<T> is a small in-process event bus that does not involve native code.

final FlDataStream<String> stream = FlDataStream<String>();
final void Function() cancel = stream.listen((String data) {
  debugPrint(data);
});

stream.send('hello');
cancel();

Sending events from native code

Create the channel from Dart first, then send events from native code.

Android (Kotlin):

FlChannelPlugin.getEventChannel("event_test")?.send(mapOf("value" to 42))

iOS and macOS (Swift):

FlChannelPlugin.getEventChannel("event_test")?.send(["value": 42])

HarmonyOS (ArkTS):

FlChannelPlugin.getEventChannel("event_test")?.send({ value: 42 });

Windows and Linux events are delivered by the plugin's C++ EventChannel implementation, so applications use the same Dart API on every desktop platform.

Web JavaScript bridge

Web platforms have no native process. Channels are simulated with a local Dart stream, and JavaScript can send events to an existing channel:

flChannelSendEvent('event_test', 'hello from JavaScript');

The channel must be created and listened to from Dart before JavaScript sends an event.

If www.gstatic.com is unreachable, self-host CanvasKit by running flutter build web --no-web-resources-cdn, or point canvasKitBaseUrl at a local canvaskit/ directory. The example app already does this in web/flutter_bootstrap.js.

Swift Package Manager

iOS and macOS sources are shared in darwin/ and expose a Package.swift, so the plugin works with both Swift Package Manager and CocoaPods.

Example

The example app demonstrates creating a channel, listening to events, pausing, resuming, disposing and sending events. It supports Android, iOS, macOS, Windows, Linux, Web and HarmonyOS.

Run it with:

cd example
flutter run

For Web:

cd example
flutter run -d chrome

To build the Web example without the gstatic CDN, use the bundled CanvasKit files:

cd example
flutter build web --no-web-resources-cdn

License

MIT

Libraries

fl_channel
fl_channel_web