🐞Tasks do not run on iOS at all

[SticksDev]

• I have read the README
• I have done the setup for Android
• I have done the setup for iOS
• I have ran the sample app and it does not work there

Version

Technology	Version
Workmanager version	latest
Xcode version	15.0.1
Swift version	latest
iOS deployment target	13

Describe the error
I have followed all of the setup steps, run the command in the debugger, and nothing happens. No errors, just the task does not get triggered at all. I both have the @pragma('vm:entry-point') on my task handler and listen for both the name and the iosbackroundtask enum. My initial print doesn't even get logged either...

Ideas? Is This a possible bug? Thanks.

Output of flutter doctor -v

[✓] Flutter (Channel stable, 3.13.9, on macOS 14.1.1 23B81 darwin-x64, locale en-US)
    • Flutter version 3.13.9 on channel stable at /usr/local/Caskroom/flutter/3.13.9/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision d211f42860 (2 weeks ago), 2023-10-25 13:42:25 -0700
    • Engine revision 0545f8705d
    • Dart version 3.1.5
    • DevTools version 2.25.0

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[✓] Xcode - develop for iOS and macOS (Xcode 15.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15A507
    • CocoaPods version 1.14.2

[✗] Chrome - develop for the web (Cannot find Chrome executable at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] IntelliJ IDEA Ultimate Edition (version 2023.2.5)
    • IntelliJ at /Users/sticks/Applications/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 76.3.4
    • Dart plugin version 232.10072.19

[✓] Connected device (2 available)
    • [omitted] iPhone (mobile) • 00008120-001A698A01E3C01E • ios        • iOS 17.0.3 21A360
    • macOS (desktop)          • macos                     • darwin-x64 • macOS 14.1.1 23B81 darwin-x64

[✓] Network resources
    • All expected network resources are available.```

[DavidIjsud]

@SticksDev are you still getting the error? if so, then what other versions of ios did you test it?

[SticksDev]

iOS 17.0.3 and I used your demo app, which also did not work.

[project4-0]

Hello I have the same problem. Background task are running on IOS only if Workmanager is initialized in debug mode = true. Workmanager().initialize(callbackDispatcher, isInDebugMode: true); If isInDebugMode = false. Does not start.

[project4-0]

I do register the oneOffTask with static method like this. On Android works. but on IOS not.
static void registerOneOffTask(
{required String taskKey,
required String taskName,
required Map<String, dynamic> inputData,
required Duration initialDelay}) {
try {
Constraints constraints = Constraints(
networkType: NetworkType.not_required,
requiresBatteryNotLow: false,
requiresCharging: false,
requiresDeviceIdle: false,
requiresStorageNotLow: false,
);
if(Platform.isIOS){
Workmanager().registerOneOffTask(taskKey, taskName,
initialDelay: initialDelay,constraints: constraints, inputData: inputData, existingWorkPolicy: ExistingWorkPolicy.append);
}else {
Workmanager().registerOneOffTask(taskKey, taskName,
initialDelay: initialDelay, inputData: inputData, existingWorkPolicy: ExistingWorkPolicy.append);
}
if (kDebugMode) {
DateTime executionTime = DateTime.now().add(initialDelay);
print('Task $taskKey will be executed at $executionTime');
}
} catch (e, s) {
if (kDebugMode) {
print('Error in registerOneOffTask');
print(e);
print(s);
}
}
}

[SticksDev]

Any updates?

[brunodmn]

I am not able to use it as well. I follow documentation in details, I even created a new project just to test this package only.

BGTaskScheduler works if I triggered by e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"task-identifier"], not on function call on flutter.

Background Fetch won't work or throw any erros (trying to trigger it by Xcode>debug>Simulate Background Fetch)

I have:

• added Background Modes capability (Background processing and background fetch)
• registered my task on AppDelegate.swift and Info.plist

background_service.dart:

import 'dart:io';

import 'package:workmanager/workmanager.dart';

@pragma(
    'vm:entry-point') // Mandatory if the App is obfuscated or using Flutter 3.1+
void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) {
    switch (task) {
      case Workmanager.iOSBackgroundTask:
        stderr.writeln("The iOS background fetch was triggered");
        print(
            "The iOS background fetch was triggered"); //simpleTask will be emitted here.
        break;
      default:
        print(
            "Native called background task: $task"); //simpleTask will be emitted here.
        break;
    }

    return Future.value(true);
  });
}

class BackgruondService {
  static Future<void> initialize() async {
    Workmanager().initialize(
        callbackDispatcher, // The top level function, aka callbackDispatcher
        isInDebugMode:
            true // If enabled it will post a notification whenever the task is running. Handy for debugging tasks
        );
    Workmanager().registerOneOffTask("task-identifier", "simpleTask");
  }
}

AppDelegate.swift:

import UIKit
import Flutter
import workmanager

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
    override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        GeneratedPluginRegistrant.register(with: self)
        // WORKMANAGER
        UNUserNotificationCenter.current().delegate = self
        WorkmanagerPlugin.setPluginRegistrantCallback { registry in
            // Registry in this case is the FlutterEngine that is created in Workmanager's
            // performFetchWithCompletionHandler or BGAppRefreshTask.
            // This will make other plugins available during a background operation.
            GeneratedPluginRegistrant.register(with: registry)
        }
        WorkmanagerPlugin.registerTask(withIdentifier: "task-identifier")
        // background fetch
        UIApplication.shared.setMinimumBackgroundFetchInterval(TimeInterval(60*15))
        // WORKMANAGER
        
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
}

Info.plist:

(...)
        <key>BGTaskSchedulerPermittedIdentifiers</key>
	<array>
		<string>task-identifier</string>
	</array>
	<key>UIBackgroundModes</key>
	<array>
		<string>fetch</string>
		<string>processing</string>
	</array>
(...)

Am I missing something? Documentation does not seem quite up to date...

[DominicGBauer]

I moved to this PR and it seems to be working for me now #511

[joonne]

Commenting now on multiple issues while debugging the issue with plugins on iOS background isolates, but it finally seems that the missing piece was this:

// AppDelegate.swift

GeneratedPluginRegistrant.register(with: self)
WorkmanagerPlugin.setPluginRegistrantCallback { registry in
  GeneratedPluginRegistrant.register(with: registry)
}

With the above added (after GeneratedPluginRegistrant.register(with: self), I'm finally able to call SharedPreferences and also the Firebase.initializeApp() successfully 🎉

I did not find this documented anywhere, I'll try to find a suitable place from the official README.

[dsourav]

Commenting now on multiple issues while debugging the issue with plugins on iOS background isolates, but it finally seems that the missing piece was this:

// AppDelegate.swift

GeneratedPluginRegistrant.register(with: self)
WorkmanagerPlugin.setPluginRegistrantCallback { registry in
  GeneratedPluginRegistrant.register(with: registry)
}

With the above added (after GeneratedPluginRegistrant.register(with: self), I'm finally able to call SharedPreferences and also the Firebase.initializeApp() successfully 🎉

I did not find this documented anywhere, I'll try to find a suitable place from the official README.

It worked.