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

Features

• Can perform repetitive task with foreground service.
• Provides useful utilities (minimizeApp, wakeUpScreen, etc.) that can use when performing task.
• Provides a widget that prevents the app from closing when the foreground service is running.
• Provides a widget to start the foreground service when the app is minimized or closed.
• Provides an option to automatically resume foreground service on boot.

Getting started

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

dependencies:
  flutter_foreground_task: ^3.4.1

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

🐤 Android

Since this plugin is based on a foreground service, we need to add the following permission to the AndroidManifest.xml file. Open the AndroidManifest.xml file and specify it between the <manifest> and <application> tags.

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

And we need to add this permission to automatically resume foreground service at boot time.

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

And specify the service inside the <application> tag as follows.

<service android:name="com.pravera.flutter_foreground_task.service.ForegroundService" />

🐤 iOS

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

• Works only on iOS 10.0 or later.
• If the app is forcibly closed, the task will not work.
• Task cannot be started automatically on device reboot.
• Due to the background processing limitations of the platform, the onEvent event may not work properly in the background. But in the foreground it works fine.

Objective-C:

1. To use this plugin developed in Swift language in a project using Objective-C, you need to add a bridge header. If you don't have an ios/Runner/Runner-Bridging-Header.h file in your project, check this page.

2. 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, Without this code the task will not work.
  [FlutterForegroundTaskPlugin setPluginRegistrantCallback:registerPlugins];

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

@end

Swift:

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

#import <flutter_foreground_task/FlutterForegroundTaskPlugin.h>

2. 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, Without this code the task will not work.
    SwiftFlutterForegroundTaskPlugin.setPluginRegistrantCallback(registerPlugins)

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

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

How to use

This plugin has two ways to start a foreground task. There is a way to manually start a foreground task and a way to start it when the app is minimized or closed by the WillStartForegroundTask widget.

🐥 Start manually

1. Initialize the FlutterForegroundTask. You can use the FlutterForegroundTask.init() function to set notifications and task options.

• androidNotificationOptions: Notification options for Android platform.
• iosNotificationOptions: Notification options for iOS platform.
• foregroundTaskOptions: Options for setting the foreground task behavior in detail.
• printDevLog: Whether to show the developer log. If this value is set to true, you can see logs of the activity (start, stop, etc) of the flutter_foreground_task plugin. It does not work in release mode. The default is false.

Future<void> _initForegroundTask() async {
  await FlutterForegroundTask.init(
    androidNotificationOptions: const AndroidNotificationOptions(
      channelId: 'notification_channel_id',
      channelName: 'Foreground Notification',
      channelDescription: 'This notification appears when the foreground service is running.',
      channelImportance: NotificationChannelImportance.LOW,
      priority: NotificationPriority.LOW,
      iconData: NotificationIconData(
        resType: ResourceType.mipmap,
        resPrefix: ResourcePrefix.ic,
        name: 'launcher',
      ),
    ),
    iosNotificationOptions: const IOSNotificationOptions(
      showNotification: true,
      playSound: false,
    ),
    foregroundTaskOptions: const ForegroundTaskOptions(
      interval: 5000,
      autoRunOnBoot: true,
      allowWifiLock: true,
    ),
    printDevLog: true,
  );
}

@override
void initState() {
  super.initState();
  _initForegroundTask();
}

2. Add WithForegroundTask widget to prevent the app from closing when the foreground service is running.

@override
Widget build(BuildContext context) {
  return MaterialApp(
    // A widget that prevents the app from closing when the foreground service is running.
    // This widget must be declared above the [Scaffold] widget.
    home: WithForegroundTask(
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter Foreground Task'),
          centerTitle: true,
        ),
        body: buildContentView(),
      ),
    ),
  );
}

3. Write callback and handler and start the foreground service. FlutterForegroundTask.startService() provides the following options:

• notificationTitle: The title that will be displayed in the notification.
• notificationText: The text that will be displayed in the notification.
• callback: A top-level function that calls the setTaskHandler function.

// The callback function should always be a top-level function.
void startCallback() {
  // The setTaskHandler function must be called to handle the task in the background.
  FlutterForegroundTask.setTaskHandler(FirstTaskHandler());
}

class FirstTaskHandler implements TaskHandler {
  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
    // You can use the getData function to get the data you saved.
    final customData = await FlutterForegroundTask.getData<String>(key: 'customData');
    print('customData: $customData');
  }

  @override
  Future<void> onEvent(DateTime timestamp, SendPort? sendPort) async {
    // Send data to the main isolate.
    sendPort?.send(timestamp);
  }

  @override
  Future<void> onDestroy(DateTime timestamp) async {
    // You can use the clearAllData function to clear all the stored data.
    await FlutterForegroundTask.clearAllData();
  }
}

class ExampleApp extends StatefulWidget {
  const ExampleApp({Key? key}) : super(key: key);

  @override
  _ExampleAppState createState() => _ExampleAppState();
}

class _ExampleAppState extends State<ExampleApp> {
  ReceivePort? _receivePort;

  // ...

  Future<bool> _startForegroundTask() async {
    // You can save data using the saveData function.
    await FlutterForegroundTask.saveData(key: 'customData', value: 'hello');

    ReceivePort? receivePort;
    if (await FlutterForegroundTask.isRunningService) {
      receivePort = await FlutterForegroundTask.restartService();
    } else {
      receivePort = await FlutterForegroundTask.startService(
        notificationTitle: 'Foreground Service is running',
        notificationText: 'Tap to return to the app',
        callback: startCallback,
      );
    }

    if (receivePort != null) {
      _receivePort = receivePort;
      _receivePort?.listen((message) {
        if (message is DateTime) {
          print('receive timestamp: $message');
        }
      });

      return true;
    }

    return false;
  }

  @override
  void dispose() {
    _receivePort?.close();
    super.dispose();
  }
}

As you can see in the code above, you can manage data with the following functions.

void function() async {
  await FlutterForegroundTask.getData(key: String);
  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 FirstTaskHandler implements TaskHandler {
  StreamSubscription<Position>? streamSubscription;

  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
    final positionStream = Geolocator.getPositionStream();
    streamSubscription = positionStream.listen((event) {
      // Update notification content.
      FlutterForegroundTask.updateService(
          notificationTitle: 'Current Position',
          notificationText: '${event.latitude}, ${event.longitude}');

      // Send data to the main isolate.
      sendPort?.send(event);
    });
  }

  @override
  Future<void> onEvent(DateTime timestamp, SendPort? sendPort) async {

  }

  @override
  Future<void> onDestroy(DateTime timestamp) async {
    await streamSubscription?.cancel();
  }
}

4. Use FlutterForegroundTask.updateService() to update the foreground service. The options are the same as the start function.

// The callback function should always be a top-level function.
void startCallback() {
  // The setTaskHandler function must be called to handle the task in the background.
  FlutterForegroundTask.setTaskHandler(FirstTaskHandler());
}

class FirstTaskHandler implements TaskHandler {
  int updateCount = 0;

  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
    // You can use the getData function to get the data you saved.
    final customData = await FlutterForegroundTask.getData<String>(key: 'customData');
    print('customData: $customData');
  }

  @override
  Future<void> onEvent(DateTime timestamp, SendPort? sendPort) async {
    FlutterForegroundTask.updateService(
        notificationTitle: 'FirstTaskHandler',
        notificationText: timestamp.toString(),
        callback: updateCount >= 10 ? updateCallback : null);

    // Send data to the main isolate.
    sendPort?.send(timestamp);
    sendPort?.send(updateCount);

    updateCount++;
  }

  @override
  Future<void> onDestroy(DateTime timestamp) async {
    // You can use the clearAllData function to clear all the stored data.
    await FlutterForegroundTask.clearAllData();
  }
}

void updateCallback() {
  FlutterForegroundTask.setTaskHandler(SecondTaskHandler());
}

class SecondTaskHandler implements TaskHandler {
  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {

  }

  @override
  Future<void> onEvent(DateTime timestamp, SendPort? sendPort) async {
    FlutterForegroundTask.updateService(
        notificationTitle: 'SecondTaskHandler',
        notificationText: timestamp.toString());

    // Send data to the main isolate.
    sendPort?.send(timestamp);
  }

  @override
  Future<void> onDestroy(DateTime timestamp) async {

  }
}

5. If you no longer use the foreground service, call FlutterForegroundTask.stopService().

Future<bool> _stopForegroundTask() async {
  return await FlutterForegroundTask.stopService();
}

🐥 Start with WillStartForegroundTask widget

@override
Widget build(BuildContext context) {
  return MaterialApp(
    // A widget to start the foreground service when the app is minimized or closed.
    // This widget must be declared above the [Scaffold] widget.
    home: WillStartForegroundTask(
      onWillStart: () async {
        // Return whether to start the foreground service.
        return true;
      },
      androidNotificationOptions: const AndroidNotificationOptions(
        channelId: 'notification_channel_id',
        channelName: 'Foreground Notification',
        channelDescription: 'This notification appears when the foreground service is running.',
        channelImportance: NotificationChannelImportance.LOW,
        priority: NotificationPriority.LOW,
        iconData: NotificationIconData(
          resType: ResourceType.mipmap,
          resPrefix: ResourcePrefix.ic,
          name: 'launcher',
        ),
      ),
      iosNotificationOptions: const IOSNotificationOptions(
        showNotification: true,
        playSound: false,
      ),
      foregroundTaskOptions: const ForegroundTaskOptions(
        interval: 5000,
        autoRunOnBoot: false,
        allowWifiLock: false,
      ),
      printDevLog: true,
      notificationTitle: 'Foreground Service is running',
      notificationText: 'Tap to return to the app',
      callback: callback,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter Foreground Task'),
          centerTitle: true,
        ),
        body: buildContentView(),
      ),
    ),
  );
}

Models

🐔 AndroidNotificationOptions

Notification options for Android platform.

Property	Description
channelId	Unique ID of the notification channel.
channelName	The name of the notification channel. This value is displayed to the user in the notification settings.
channelDescription	The description of the notification channel. This value is displayed to the user in the notification settings.
channelImportance	The importance of the notification channel. The default is NotificationChannelImportance.DEFAULT.
priority	Priority of notifications for Android 7.1 and lower. The default is NotificationPriority.DEFAULT.
enableVibration	Whether to enable vibration when creating notifications. The default is false.
playSound	Whether to play sound when creating notifications. The default is false.
showWhen	Whether to show the timestamp when the notification was created in the content view. The default is false.
isSticky	Whether or not the system will restart the service if the service is killed. The default is true.
visibility	Control the level of detail displayed in notifications on the lock screen. The default is NotificationVisibility.VISIBILITY_PUBLIC.
iconData	The data of the icon to display in the notification. If the value is null, the app launcher icon is used.

🐔 NotificationIconData

Data for setting the notification icon.

Property	Description
resType	The resource type of the notification icon. If the resource is in the drawable folder, set it to ResourceType.drawable, if the resource is in the mipmap folder, set it to ResourceType.mipmap.
resPrefix	The resource prefix of the notification icon. If the notification icon name is ic_simple_notification, set it to ResourcePrefix.ic and set name to simple_notification.
name	Notification icon name without prefix.

🐔 ResourceType

The resource type of the notification icon.

Value	Description
drawable	A resources in the drawable folder. The drawable folder is where all kinds of images are stored.
mipmap	A resources in the mipmap folder. The mipmap folder is usually where the launcher icon image is stored.

🐔 ResourcePrefix

The resource prefix of the notification icon.

Value	Description
ic	A resources with the ic_ prefix.
img	A resources with the img_ prefix.

🐔 IOSNotificationOptions

Notification options for iOS platform.

Property	Description
showNotification	Whether to show notifications. The default is true.
playSound	Whether to play sound when creating notifications. The default is false.

🐔 ForegroundTaskOptions

Data class with foreground task options.

Property	Description
interval	The task call interval in milliseconds. The default is 5000.
autoRunOnBoot	Whether to automatically run foreground task on boot. The default is false.
allowWifiLock	Allows an application to keep the Wi-Fi radio awake. The default is false.

🐔 NotificationChannelImportance

The importance of the notification channel. See https://developer.android.com/training/notify-user/channels?hl=ko#importance

Value	Description
NONE	A notification with no importance: does not show in the shade.
MIN	Min notification importance: only shows in the shade, below the fold.
LOW	Low notification importance: shows in the shade, and potentially in the status bar (see shouldHideSilentStatusBarIcons()), but is not audibly intrusive.
DEFAULT	Default notification importance: shows everywhere, makes noise, but does not visually intrude.
HIGH	Higher notification importance: shows everywhere, makes noise and peeks. May use full screen intents.
MAX	Max notification importance: same as HIGH, but generally not used.

🐔 NotificationPriority

Priority of notifications for Android 7.1 and lower.

Value	Description
MIN	No sound and does not appear in the status bar.
LOW	No sound.
DEFAULT	Makes a sound.
HIGH	Makes a sound and appears as a heads-up notification.
MAX	Same as HIGH, but used when you want to notify notification immediately.

🐔 NotificationVisibility

The level of detail displayed in notifications on the lock screen.

Value	Description
VISIBILITY_PUBLIC	Show this notification in its entirety on all lockscreens.
VISIBILITY_SECRET	Do not reveal any part of this notification on a secure lockscreen.
VISIBILITY_PRIVATE	Show this notification on all lockscreens, but conceal sensitive or private information on secure lockscreens.

Utility methods

🍭 minimizeApp

Minimize the app to the background.

import 'package:flutter_foreground_task/flutter_foreground_task.dart';

void function() => FlutterForegroundTask.minimizeApp();

🍭 wakeUpScreen

Wake up the screen of a device that is turned off.

import 'package:flutter_foreground_task/flutter_foreground_task.dart';

void function() => FlutterForegroundTask.wakeUpScreen();

🍭 isIgnoringBatteryOptimizations

Returns whether the app has been excluded from battery optimization.

import 'package:flutter_foreground_task/flutter_foreground_task.dart';

Future<bool> function() => FlutterForegroundTask.isIgnoringBatteryOptimizations;

🍭 openIgnoreBatteryOptimizationSettings

Open the settings page where you can set ignore battery optimization.

import 'package:flutter_foreground_task/flutter_foreground_task.dart';

Future<bool> function() => FlutterForegroundTask.openIgnoreBatteryOptimizationSettings();

🍭 requestIgnoreBatteryOptimization

Request to ignore battery optimization. This function requires android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS permission.

import 'package:flutter_foreground_task/flutter_foreground_task.dart';

Future<bool> function() => FlutterForegroundTask.requestIgnoreBatteryOptimization();

Support

If you find any bugs or issues while using the plugin, please register an issues on GitHub. You can also contact us at hwj930513@naver.com.