Running Tasks when the app is not in the App switcher

See my explanation of this in iOS Background Execution Limits.

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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Thank you @DTS Engineer. As per the WWDC 2019 video, I've updated the native code to run a background task every 15 minutes in my Flutter project. However, it does not work for me.

After adding fetch to the background modes in the capabilities and adding task_id to the Info.plist, I added the following code block to the AppDelegate.swift. Despite this, it didn't work for me. When I simulated this as per the video, it did not simulate periodically like it happens in the video but only ran once.

Can you please help me?

override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
) -> Bool {

    #if NON_REALM
    NSLog("FOUND NON_REALM BUILD")
    #endif

    let bundleID = Bundle.main.bundleIdentifier
    NSLog("Loaded bundle id: \(bundleID)")

    let controller: FlutterViewController = window?.rootViewController as! FlutterViewController
    agentChannel = FlutterMethodChannel(
        name: "mobile.cloudbrink/brinkagent",
        binaryMessenger: controller.binaryMessenger
    )

    // Method-channel invocation from Flutter (Dart)
    methodChannelInvocationFromUI()
    notifyVPNStatusChange()

    reInitFlagsBasedOnStatus()
    GeneratedPluginRegistrant.register(with: self)

    BGTaskScheduler.shared.register(forTaskWithIdentifier: "com.cloudbrink.refresh", using: nil) { task in
        self.handleAppRefresh(task: task as! BGAppRefreshTask)
    }

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

override func applicationDidEnterBackground(_ application: UIApplication) {
    scheduleAppRefresh()
}

func scheduleAppRefresh() {
    let request = BGAppRefreshTaskRequest(identifier: "com.cloudbrink.refresh")
    request.earliestBeginDate = Date(timeIntervalSinceNow: 15 * 60) // 15 minutes

    do {
        try BGTaskScheduler.shared.submit(request)
    } catch {
        print("Could not schedule app refresh: \(error)")
    }
}

// Refresh task handler
func handleAppRefresh(task: BGAppRefreshTask) {
    print("Before schedule")
    scheduleAppRefresh()
    print("After schedule")

    let queue = OperationQueue()
    queue.addOperation {
        // Perform your background refresh operation
        print("Doing the background task.")
        task.setTaskCompleted(success: true)
    }

    task.expirationHandler = {
        queue.cancelAllOperations()
        task.setTaskCompleted(success: false)
    }
}