This plugin is used to implement a foreground service on the Android platform.
- 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 that can start the foreground service when the app is minimized or closed.
- Provides an option to automatically resume foreground service on boot.
To use this plugin, add flutter_foreground_task
as a dependency in your pubspec.yaml file. For example:
dependencies:
flutter_foreground_task: ^6.0.0+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.
Open the AndroidManifest.xml
file and specify the service inside the <application>
tag as follows. If you want the foreground service to run only when the app is running, add android:stopWithTask
option.
<!-- Add android:stopWithTask option only when necessary. -->
<service
android:name="com.pravera.flutter_foreground_task.service.ForegroundService"
android:stopWithTask="true" />
We can also launch flutter_foreground_task
on the 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
onRepeatEvent
event may not work properly in the background. But in the foreground it works fine.
Objective-C:
-
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. -
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];
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, Without this code the task will not work.
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)
}
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.
- Initialize the
FlutterForegroundTask
. You can use theFlutterForegroundTask.init()
function to set notifications and task options.
androidNotificationOptions
: Options for setting up notifications on the Android platform.iosNotificationOptions
: Options for setting up notifications on the iOS platform.foregroundTaskOptions
: Options for setting the foreground task.
void _initForegroundTask() {
FlutterForegroundTask.init(
androidNotificationOptions: 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: const NotificationIconData(
resType: ResourceType.mipmap,
resPrefix: ResourcePrefix.ic,
name: 'launcher',
),
buttons: [
const NotificationButton(id: 'sendButton', text: 'Send'),
const NotificationButton(id: 'testButton', text: 'Test'),
],
),
iosNotificationOptions: const IOSNotificationOptions(
showNotification: true,
playSound: false,
),
foregroundTaskOptions: const ForegroundTaskOptions(
interval: 5000,
isOnceEvent: false,
autoRunOnBoot: true,
allowWakeLock: true,
allowWifiLock: true,
),
);
}
@override
void initState() {
super.initState();
_initForegroundTask();
}
- Add
WithForegroundTask
widget to prevent the app from closing when the foreground service is running.
@override
Widget build(BuildContext context) {
// A widget that prevents the app from closing when the foreground service is running.
// This widget must be declared above the [Scaffold] widget.
return WithForegroundTask(
child: Scaffold(
appBar: AppBar(
title: const Text('Flutter Foreground Task'),
centerTitle: true,
),
body: buildContentView(),
),
);
}
- 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.
@pragma('vm:entry-point')
void startCallback() {
// The setTaskHandler function must be called to handle the task in the background.
FlutterForegroundTask.setTaskHandler(FirstTaskHandler());
}
class FirstTaskHandler extends TaskHandler {
SendPort? _sendPort;
// Called when the task is started.
@override
Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
_sendPort = sendPort;
// You can use the getData function to get the stored data.
final customData =
await FlutterForegroundTask.getData<String>(key: 'customData');
print('customData: $customData');
}
// Called every [interval] milliseconds in [ForegroundTaskOptions].
@override
Future<void> onRepeatEvent(DateTime timestamp, SendPort? sendPort) async {
// Send data to the main isolate.
sendPort?.send(timestamp);
}
// Called when the notification button on the Android platform is pressed.
@override
Future<void> onDestroy(DateTime timestamp, SendPort? sendPort) async {
}
// Called when the notification button on the Android platform is pressed.
@override
void onNotificationButtonPressed(String id) {
print('onNotificationButtonPressed >> $id');
}
// Called when the notification itself on the Android platform is pressed.
//
// "android.permission.SYSTEM_ALERT_WINDOW" permission must be granted for
// this function to be called.
@override
void onNotificationPressed() {
// Note that the app will only route to "/resume-route" when it is exited so
// it will usually be necessary to send a message through the send port to
// signal it to restore state when the app is already started.
FlutterForegroundTask.launchApp("/resume-route");
_sendPort?.send('onNotificationPressed');
}
}
class ExampleApp extends StatelessWidget {
const ExampleApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
initialRoute: '/',
routes: {
'/': (context) => const ExamplePage(),
'/resume-route': (context) => const ResumeRoutePage(),
},
);
}
}
class ExamplePage extends StatefulWidget {
const ExamplePage({Key? key}) : super(key: key);
@override
State<StatefulWidget> createState() => _ExamplePageState();
}
class _ExamplePageState extends State<ExamplePage> {
ReceivePort? _receivePort;
// ...
Future<void> _requestPermissionForAndroid() async {
if (!Platform.isAndroid) {
return;
}
// "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 or higher, 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();
}
// Android 13 and higher, you need to allow notification permission to expose foreground service notification.
final NotificationPermission notificationPermissionStatus =
await FlutterForegroundTask.checkNotificationPermission();
if (notificationPermissionStatus != NotificationPermission.granted) {
await FlutterForegroundTask.requestNotificationPermission();
}
}
Future<bool> _startForegroundTask() async {
// You can save data using the saveData function.
await FlutterForegroundTask.saveData(key: 'customData', value: 'hello');
// Register the receivePort before starting the service.
final ReceivePort? receivePort = FlutterForegroundTask.receivePort;
final bool isRegistered = _registerReceivePort(receivePort);
if (!isRegistered) {
print('Failed to register receivePort!');
return false;
}
if (await FlutterForegroundTask.isRunningService) {
return FlutterForegroundTask.restartService();
} else {
return FlutterForegroundTask.startService(
notificationTitle: 'Foreground Service is running',
notificationText: 'Tap to return to the app',
callback: startCallback,
);
}
}
bool _registerReceivePort(ReceivePort? newReceivePort) {
if (newReceivePort == null) {
return false;
}
_closeReceivePort();
_receivePort = newReceivePort;
_receivePort?.listen((data) {
if (data is int) {
print('eventCount: $data');
} else if (data is String) {
if (data == 'onNotificationPressed') {
Navigator.of(context).pushNamed('/resume-route');
}
} else if (data is DateTime) {
print('timestamp: ${data.toString()}');
}
});
return _receivePort != null;
}
void _closeReceivePort() {
_receivePort?.close();
_receivePort = null;
}
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) async {
await _requestPermissionForAndroid();
_initForegroundTask();
// You can get the previous ReceivePort without restarting the service.
if (await FlutterForegroundTask.isRunningService) {
final newReceivePort = FlutterForegroundTask.receivePort;
_registerReceivePort(newReceivePort);
}
});
}
@override
void dispose() {
_closeReceivePort();
super.dispose();
}
}
class ResumeRoutePage extends StatelessWidget {
const ResumeRoutePage({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Resume Route'),
centerTitle: true,
),
body: Center(
child: ElevatedButton(
onPressed: () {
// Navigate back to first route when tapped.
Navigator.of(context).pop();
},
child: const Text('Go back!'),
),
),
);
}
}
As you can see in the code above, you can manage data with the following functions.
void function() async {
await FlutterForegroundTask.getData(key: String);
await FlutterForegroundTask.getAllData();
await FlutterForegroundTask.saveData(key: String, value: Object);
await FlutterForegroundTask.removeData(key: String);
await FlutterForegroundTask.clearAllData();
}
If the plugin you want to use provides a stream, use it like this:
class FirstTaskHandler extends TaskHandler {
StreamSubscription<Location>? _streamSubscription;
@override
Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
_streamSubscription = FlLocation.getLocationStream().listen((location) {
FlutterForegroundTask.updateService(
notificationTitle: 'My Location',
notificationText: '${location.latitude}, ${location.longitude}',
);
// Send data to the main isolate.
sendPort?.send(location);
});
}
@override
Future<void> onRepeatEvent(DateTime timestamp, SendPort? sendPort) async {
}
@override
Future<void> onDestroy(DateTime timestamp, SendPort? sendPort) async {
await _streamSubscription?.cancel();
}
}
- 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.
@pragma('vm:entry-point')
void startCallback() {
// The setTaskHandler function must be called to handle the task in the background.
FlutterForegroundTask.setTaskHandler(FirstTaskHandler());
}
class FirstTaskHandler extends TaskHandler {
int _eventCount = 0;
@override
Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
}
@override
Future<void> onRepeatEvent(DateTime timestamp, SendPort? sendPort) async {
if (_eventCount == 10) {
FlutterForegroundTask.updateService(
foregroundTaskOptions: const ForegroundTaskOptions(interval: 1000),
callback: updateCallback,
);
} else {
FlutterForegroundTask.updateService(
notificationTitle: 'FirstTaskHandler',
notificationText: timestamp.toString(),
);
// Send data to the main isolate.
sendPort?.send(_eventCount);
_eventCount++;
}
}
@override
Future<void> onDestroy(DateTime timestamp, SendPort? sendPort) async {
}
}
@pragma('vm:entry-point')
void updateCallback() {
FlutterForegroundTask.setTaskHandler(SecondTaskHandler());
}
class SecondTaskHandler extends TaskHandler {
@override
Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
}
@override
Future<void> onRepeatEvent(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, SendPort? sendPort) async {
}
}
- If you no longer use the foreground service, call
FlutterForegroundTask.stopService()
.
Future<bool> _stopForegroundTask() {
return FlutterForegroundTask.stopService();
}
<service
android:name="com.pravera.flutter_foreground_task.service.ForegroundService"
android:stopWithTask="true" /> <!-- important -->
Future<void> _requestPermissionForAndroid() async {
if (!Platform.isAndroid) {
return;
}
// "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 or higher, 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();
}
// Android 13 and higher, you need to allow notification permission to expose foreground service notification.
final NotificationPermission notificationPermissionStatus =
await FlutterForegroundTask.checkNotificationPermission();
if (notificationPermissionStatus != NotificationPermission.granted) {
await FlutterForegroundTask.requestNotificationPermission();
}
}
void _onData(dynamic data) {
if (data is int) {
print('eventCount: $data');
} else if (data is String) {
if (data == 'onNotificationPressed') {
Navigator.of(context).pushNamed('/resume-route');
}
} else if (data is DateTime) {
print('timestamp: ${data.toString()}');
}
}
@override
void initState() {
super.initState();
_requestPermissionForAndroid();
}
@override
Widget build(BuildContext context) {
return MaterialApp(
// A widget that can 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: AndroidNotificationOptions(
channelId: 'notification_channel_id',
channelName: 'Foreground Notification',
channelDescription: 'This notification appears when the foreground service is running.',
channelImportance: NotificationChannelImportance.LOW,
priority: NotificationPriority.LOW,
isSticky: false, // important
iconData: const NotificationIconData(
resType: ResourceType.mipmap,
resPrefix: ResourcePrefix.ic,
name: 'launcher',
),
buttons: [
const NotificationButton(id: 'sendButton', text: 'Send'),
const NotificationButton(id: 'testButton', text: 'Test'),
],
),
iosNotificationOptions: const IOSNotificationOptions(
showNotification: true,
playSound: false,
),
foregroundTaskOptions: const ForegroundTaskOptions(
interval: 5000,
isOnceEvent: false,
allowWakeLock: false,
allowWifiLock: false,
),
notificationTitle: 'Foreground Service is running',
notificationText: 'Tap to return to the app',
callback: startCallback,
onData: _onData,
child: Scaffold(
appBar: AppBar(
title: const Text('Flutter Foreground Task'),
centerTitle: true,
),
body: buildContentView(),
),
),
);
}
Notification options for Android platform.
Property | Description |
---|---|
id |
Unique ID of the notification. |
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 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. |
buttons |
A list of buttons to display in the notification. A maximum of 3 is allowed. |
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. |
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. |
The resource prefix of the notification icon.
Value | Description |
---|---|
ic |
A resources with the ic_ prefix. |
img |
A resources with the img_ prefix. |
The button to display in the notification.
Property | Description |
---|---|
id |
The button identifier. |
text |
The text to display on the button. |
textColor |
The button text color. |
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 . |
Data class with foreground task options.
Property | Description |
---|---|
interval |
The task call interval in milliseconds. The default is 5000 . |
isOnceEvent |
Whether to invoke the onRepeatEvent of TaskHandler only once. The default is false . |
autoRunOnBoot |
Whether to automatically run foreground task on boot. The default is false . |
allowWakeLock |
Whether to keep the CPU turned on. The default is true . |
allowWifiLock |
Allows an application to keep the Wi-Fi radio awake. The default is false . |
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. |
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. |
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. |
Minimize the app to the background.
Warning It only works when the app is in the foreground.
void function() => FlutterForegroundTask.minimizeApp();
Launch the app if it is not running otherwise open the current activity.
void function() => FlutterForegroundTask.launchApp();
It is also possible to pass a route to this function but the route will only be loaded if the app is not already running.
Wake up the screen of a device that is turned off.
void function() => FlutterForegroundTask.wakeUpScreen();
Returns whether the app has been excluded from battery optimization.
Future<bool> function() => FlutterForegroundTask.isIgnoringBatteryOptimizations;
Open the settings page where you can set ignore battery optimization.
Warning It only works when the app is in the foreground.
Future<bool> function() => FlutterForegroundTask.openIgnoreBatteryOptimizationSettings();
Request to ignore battery optimization. This function requires android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS
permission.
Warning It only works when the app is in the foreground.
Future<bool> function() => FlutterForegroundTask.requestIgnoreBatteryOptimization();
Returns whether the "android.permission.SYSTEM_ALERT_WINDOW" permission was granted.
Future<bool> function() => FlutterForegroundTask.canDrawOverlays;
Open the settings page where you can allow/deny the "android.permission.SYSTEM_ALERT_WINDOW" permission.
Warning It only works when the app is in the foreground.
Future<bool> function() => FlutterForegroundTask.openSystemAlertWindowSettings();
Returns whether the app is in the foreground.
Future<bool> function() => FlutterForegroundTask.isAppOnForeground;
Toggles lockScreen visibility.
Warning It only works when the app is in the foreground.
void function() => FlutterForegroundTask.setOnLockScreenVisibility(true);
Returns "android.permission.POST_NOTIFICATIONS" permission status.
for Android 13, https://developer.android.com/develop/ui/views/notifications/notification-permission
Warning It only works when the app is in the foreground.
Future<NotificationPermission> function() => FlutterForegroundTask.checkNotificationPermission();
Request "android.permission.POST_NOTIFICATIONS" permission.
for Android 13, https://developer.android.com/develop/ui/views/notifications/notification-permission
Warning It only works when the app is in the foreground.
Future<NotificationPermission> function() => FlutterForegroundTask.requestNotificationPermission();
If you find any bugs or issues while using the plugin, please register an issues on GitHub. You can also contact us at [email protected].