flutter_foreground_task 8.9.0

This plugin is used to implement a foreground service on the Android platform.

This plugin is used to implement a foreground service on the Android platform.

Features

• Can perform repetitive tasks with the foreground service.
• Supports two-way communication between the foreground service and UI.
• Provides widget that minimize the app without closing it when the user presses the soft back button.
• Provides useful utilities that can use while performing tasks.
• Provides option to automatically resume the foreground service on boot.

Support version

• Flutter: 3.10.0+
• Dart: 3.0.0+
• Android: 5.0+ (minSdkVersion: 21)
• iOS: 13.0+

Getting started

To use this plugin, add flutter_foreground_task as a dependency in your pubspec.yaml file. For example:

dependencies:
  flutter_foreground_task: ^8.9.0

After adding the flutter_foreground_task plugin to the flutter project, we need to specify the permissions and service to use for this plugin to work properly.

🐤 Android

Open the AndroidManifest.xml file and specify the service tag inside the <application> tag as follows.

If you want the foreground service to run only when the app is running, add android:stopWithTask="true" option.

As mentioned in the Android guidelines, to start a FG service on Android 14+, you must specify android:foregroundServiceType.

You can read all the details in the Android Developer Page : https://developer.android.com/about/versions/14/changes/fgs-types-required

<!-- required -->
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

<!-- foregroundServiceType: dataSync -->
<uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />

<!-- foregroundServiceType: remoteMessaging -->
<uses-permission android:name="android.permission.FOREGROUND_SERVICE_REMOTE_MESSAGING" />

<!-- Warning: Do not change service name. -->
<service 
    android:name="com.pravera.flutter_foreground_task.service.ForegroundService"
    android:foregroundServiceType="dataSync|remoteMessaging"
    android:exported="false" />

Check runtime requirements before starting the service. If this requirement is not met, the foreground service cannot be started.

🐤 iOS

We can also launch flutter_foreground_task on the iOS platform. However, it has the following limitations.

• If you force close an app in recent apps, the task will be destroyed immediately.
• The task cannot be started automatically on boot like Android OS.
• The task runs in the background for approximately 30 seconds every 15 minutes. This may take longer than 15 minutes due to iOS limitations.

Info.plist:

Add the key below to ios/Runner/info.plist file so that the task can run in the background.

<key>BGTaskSchedulerPermittedIdentifiers</key>
<array>
    <string>com.pravera.flutter_foreground_task.refresh</string>
</array>
<key>UIBackgroundModes</key>
<array>
    <string>fetch</string>
</array>

Objective-C:

To use this plugin developed in Swift in a project using Objective-C, you need to add a bridge header. If there is no ios/Runner/Runner-Bridging-Header.h file in your project, check this page.

Open the ios/Runner/AppDelegate.swift file and add the commented code.

#import "AppDelegate.h"
#import "GeneratedPluginRegistrant.h"

// here
#import <flutter_foreground_task/FlutterForegroundTaskPlugin.h>

// here
void registerPlugins(NSObject<FlutterPluginRegistry>* registry) {
  [GeneratedPluginRegistrant registerWithRegistry:registry];
}

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [GeneratedPluginRegistrant registerWithRegistry:self];

  // here
  [FlutterForegroundTaskPlugin setPluginRegistrantCallback:registerPlugins];
  if (@available(iOS 10.0, *)) {
    [UNUserNotificationCenter currentNotificationCenter].delegate = (id<UNUserNotificationCenterDelegate>) self;
  }

  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end

Swift:

Declare the import statement below in the ios/Runner/Runner-Bridging-Header.h file.

#import <flutter_foreground_task/FlutterForegroundTaskPlugin.h>

Open the ios/Runner/AppDelegate.swift file and add the commented code.

import UIKit
import Flutter

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)

    // here
    SwiftFlutterForegroundTaskPlugin.setPluginRegistrantCallback(registerPlugins)
    if #available(iOS 10.0, *) {
      UNUserNotificationCenter.current().delegate = self as? UNUserNotificationCenterDelegate
    }

    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

// here
func registerPlugins(registry: FlutterPluginRegistry) {
  GeneratedPluginRegistrant.register(with: registry)
}

How to use

🐥 step by step

1. Initialize port for communication between TaskHandler and UI.

void main() {
  // Initialize port for communication between TaskHandler and UI.
  FlutterForegroundTask.initCommunicationPort();
  runApp(const ExampleApp());
}

2. Write a TaskHandler and a callback to request starting a TaskHandler.

// The callback function should always be a top-level function.
@pragma('vm:entry-point')
void startCallback() {
  // The setTaskHandler function must be called to handle the task in the background.
  FlutterForegroundTask.setTaskHandler(MyTaskHandler());
}

class MyTaskHandler extends TaskHandler {
  // Called when the task is started.
  @override
  void onStart(DateTime timestamp, TaskStarter starter) {
    print('onStart(starter: ${starter.name})');
  }

  // Called by eventAction in [ForegroundTaskOptions].
  // - nothing() : Not use onRepeatEvent callback.
  // - once() : Call onRepeatEvent only once.
  // - repeat(interval) : Call onRepeatEvent at milliseconds interval.
  @override
  void onRepeatEvent(DateTime timestamp) {
    // Send data to main isolate.
    final Map<String, dynamic> data = {
      "timestampMillis": timestamp.millisecondsSinceEpoch,
    };
    FlutterForegroundTask.sendDataToMain(data);
  }

  // Called when the task is destroyed.
  @override
  void onDestroy(DateTime timestamp) {
    print('onDestroy');
  }

  // Called when data is sent using [FlutterForegroundTask.sendDataToTask].
  @override
  void onReceiveData(Object data) {
    print('onReceiveData: $data');
  }

  // Called when the notification button is pressed.
  @override
  void onNotificationButtonPressed(String id) {
    print('onNotificationButtonPressed: $id');
  }

  // Called when the notification itself is pressed.
  //
  // AOS: "android.permission.SYSTEM_ALERT_WINDOW" permission must be granted
  // for this function to be called.
  @override
  void onNotificationPressed() {
    FlutterForegroundTask.launchApp('/');
    print('onNotificationPressed');
  }

  // Called when the notification itself is dismissed.
  //
  // AOS: only work Android 14+
  // iOS: only work iOS 10+
  @override
  void onNotificationDismissed() {
    print('onNotificationDismissed');
  }
}

3. Add a callback to receive data sent from the TaskHandler. If the screen or controller is disposed, be sure to call the removeTaskDataCallback function.

void _onReceiveTaskData(Object data) {
  if (data is Map<String, dynamic>) {
    final dynamic timestampMillis = data["timestampMillis"];
    if (timestampMillis != null) {
      final DateTime timestamp =
          DateTime.fromMillisecondsSinceEpoch(timestampMillis, isUtc: true);
      print('timestamp: ${timestamp.toString()}');
    }
  }
}

@override
void initState() {
  super.initState();
  // Add a callback to receive data sent from the TaskHandler.
  FlutterForegroundTask.addTaskDataCallback(_onReceiveTaskData);
}

@override
void dispose() {
  // Remove a callback to receive data sent from the TaskHandler.
  FlutterForegroundTask.removeTaskDataCallback(_onReceiveTaskData);
  super.dispose();
}

4. Request permissions and initialize the service.

Future<void> _requestPermissions() async {
  // Android 13+, you need to allow notification permission to display foreground service notification.
  //
  // iOS: If you need notification, ask for permission.
  final NotificationPermission notificationPermission =
      await FlutterForegroundTask.checkNotificationPermission();
  if (notificationPermission != NotificationPermission.granted) {
    await FlutterForegroundTask.requestNotificationPermission();
  }

  if (Platform.isAndroid) {
    // "android.permission.SYSTEM_ALERT_WINDOW" permission must be granted for
    // onNotificationPressed function to be called.
    //
    // When the notification is pressed while permission is denied,
    // the onNotificationPressed function is not called and the app opens.
    //
    // If you do not use the onNotificationPressed or launchApp function,
    // you do not need to write this code.
    if (!await FlutterForegroundTask.canDrawOverlays) {
      // This function requires `android.permission.SYSTEM_ALERT_WINDOW` permission.
      await FlutterForegroundTask.openSystemAlertWindowSettings();
    }

    // Android 12+, there are restrictions on starting a foreground service.
    //
    // To restart the service on device reboot or unexpected problem, you need to allow below permission.
    if (!await FlutterForegroundTask.isIgnoringBatteryOptimizations) {
      // This function requires `android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS` permission.
      await FlutterForegroundTask.requestIgnoreBatteryOptimization();
    }

    // Use this utility only if you provide services that require long-term survival,
    // such as exact alarm service, healthcare service, or Bluetooth communication.
    //
    // This utility requires the "android.permission.SCHEDULE_EXACT_ALARM" permission.
    // Using this permission may make app distribution difficult due to Google policy.
    if (!await FlutterForegroundTask.canScheduleExactAlarms) {
      // When you call this function, will be gone to the settings page. 
      // So you need to explain to the user why set it.
      await FlutterForegroundTask.openAlarmsAndRemindersSettings();
    }
  }
}

void _initService() {
  FlutterForegroundTask.init(
    androidNotificationOptions: AndroidNotificationOptions(
      channelId: 'foreground_service',
      channelName: 'Foreground Service Notification',
      channelDescription:
          'This notification appears when the foreground service is running.',
      channelImportance: NotificationChannelImportance.LOW,
      priority: NotificationPriority.LOW,
    ),
    iosNotificationOptions: const IOSNotificationOptions(
      showNotification: false,
      playSound: false,
    ),
    foregroundTaskOptions: ForegroundTaskOptions(
      eventAction: ForegroundTaskEventAction.repeat(5000),
      autoRunOnBoot: true,
      autoRunOnMyPackageReplaced: true,
      allowWakeLock: true,
      allowWifiLock: true,
    ),
  );
}

@override
void initState() {
  super.initState();
  // Add a callback to receive data sent from the TaskHandler.
  FlutterForegroundTask.addTaskDataCallback(_onReceiveTaskData);

  WidgetsBinding.instance.addPostFrameCallback((_) {
    // Request permissions and initialize the service.
    _requestPermissions();
    _initService();
  });
}

5. Use FlutterForegroundTask.startService to start the service. startService provides the following options:

• serviceId: The unique ID that identifies the service.
• notificationTitle: The title to display in the notification.
• notificationText: The text to display in the notification.
• notificationIcon: The icon to display in the notification. (only work Android)
• notificationButtons: The buttons to display in the notification. (can add 0~3 buttons)
• callback: A top-level function that calls the setTaskHandler function.

Future<ServiceRequestResult> _startService() async {
  if (await FlutterForegroundTask.isRunningService) {
    return FlutterForegroundTask.restartService();
  } else {
    return FlutterForegroundTask.startService(
      serviceId: 256,
      notificationTitle: 'Foreground Service is running',
      notificationText: 'Tap to return to the app',
      notificationIcon: null,
      notificationButtons: [
        const NotificationButton(id: 'btn_hello', text: 'hello'),
      ],
      callback: startCallback,
    );
  }
}

Note

iOS Platform, notificationButtons is not displayed directly in notification. When the user slides down the notification, the button is displayed, so you need to guide the user on how to use it. https://developer.apple.com/documentation/usernotifications/declaring-your-actionable-notification-types

If you know a better implementation, please let me know on GitHub :)

6. Use FlutterForegroundTask.updateService to update the service. The options are the same as the start function.

@pragma('vm:entry-point')
void startCallback() {
  FlutterForegroundTask.setTaskHandler(FirstTaskHandler());
}

class FirstTaskHandler extends TaskHandler {
  int _count = 0;

  @override
  void onStart(DateTime timestamp, TaskStarter starter) {
    // some code
  }

  @override
  void onRepeatEvent(DateTime timestamp) {
    _count++;
    
    if (_count == 10) {
      FlutterForegroundTask.updateService(
        foregroundTaskOptions: ForegroundTaskOptions(
          eventAction: ForegroundTaskEventAction.repeat(1000),
        ),
        callback: updateCallback,
      );
    } else {
      FlutterForegroundTask.updateService(
        notificationTitle: 'FirstTask',
        notificationText: timestamp.toString(),
      );

      // Send data to main isolate.
      final Map<String, dynamic> data = {
        "timestampMillis": timestamp.millisecondsSinceEpoch,
      };
      FlutterForegroundTask.sendDataToMain(data);
    }
  }

  @override
  void onDestroy(DateTime timestamp) {
    // some code
  }
}

@pragma('vm:entry-point')
void updateCallback() {
  FlutterForegroundTask.setTaskHandler(SecondTaskHandler());
}

class SecondTaskHandler extends TaskHandler {
  @override
  void onStart(DateTime timestamp, TaskStarter starter) {
    // some code
  }

  @override
  void onRepeatEvent(DateTime timestamp) {
    FlutterForegroundTask.updateService(
      notificationTitle: 'SecondTask',
      notificationText: timestamp.toString(),
    );

    // Send data to main isolate.
    final Map<String, dynamic> data = {
      "timestampMillis": timestamp.millisecondsSinceEpoch,
    };
    FlutterForegroundTask.sendDataToMain(data);
  }

  @override
  void onDestroy(DateTime timestamp) {
    // some code
  }
}

7. If you no longer use the service, call FlutterForegroundTask.stopService.

Future<ServiceRequestResult> _stopService() async {
  return FlutterForegroundTask.stopService();
}

🐥 deepening

This plugin supports two-way communication between TaskHandler and UI.

The send function can only send primitive type(int, double, bool), String, Collection(Map, List) provided by Flutter.

If you want to send a custom object, send it in String format using jsonEncode and jsonDecode.

JSON and serialization >> https://docs.flutter.dev/data-and-backend/serialization/json

// TaskHandler
@override
void onStart(DateTime timestamp, TaskStarter starter) {
  // TaskHandler -> Main(UI)
  FlutterForegroundTask.sendDataToMain(Object);
}

// Main(UI)
void _onReceiveTaskData(Object data) {
  print('onReceiveTaskData: $data');
}

// Main(UI)
void _sendDataToTask() {
  // Main(UI) -> TaskHandler
  //
  // The Map collection can only be sent in json format, such as Map<String, dynamic>.
  FlutterForegroundTask.sendDataToTask(Object);
}

// TaskHandler
@override
void onReceiveData(Object data) {
  print('onReceiveData: $data');

  // You can cast it to any type you want using the Collection.cast<T> function.
  if (data is List<dynamic>) {
    final List<int> intList = data.cast<int>();
  }
}

And there are some functions for storing and managing data that are only used in this plugin.

void function() async {
  await FlutterForegroundTask.getData(key: String);
  await FlutterForegroundTask.getAllData();
  await FlutterForegroundTask.saveData(key: String, value: Object);
  await FlutterForegroundTask.removeData(key: String);
  await FlutterForegroundTask.clearAllData();
}

If the plugin you want to use provides a stream, use it like this:

class MyTaskHandler extends TaskHandler {
  StreamSubscription<Location>? _streamSubscription;

  @override
  void onStart(DateTime timestamp, TaskStarter starter) {
    _streamSubscription = FlLocation.getLocationStream().listen((location) {
      final String message = '${location.latitude}, ${location.longitude}';
      FlutterForegroundTask.updateService(notificationText: message);

      // Send data to main isolate.
      final String locationJson = jsonEncode(location.toJson());
      FlutterForegroundTask.sendDataToMain(locationJson);
    });
  }

  @override
  void onRepeatEvent(DateTime timestamp) {
    // not use
  }

  @override
  void onDestroy(DateTime timestamp) {
    _streamSubscription?.cancel();
    _streamSubscription = null;
  }
}

🐥 other example

• internal_plugin_service (Recommend)
• location_service
• record_service

More Documentation

Go here to learn about the models provided by this plugin.

Go here to learn about the utility provided by this plugin.

Go here to migrate to the new version.

Support

If you find any bugs or issues while using the plugin, please register an issues on GitHub. You can also contact us at [e-mail].