Can anyone help getting BGTaskScheduler implemented in swiftui?

Question

hope everyones doing well! I've been trying to implement BGTaskScheduler so that my app can refresh a feed in the background and schedule some local notifications. I've read over pretty much every article/question I can find on BGTaskScheduler and I can't find any definitive implementations of it. I've downloaded the apple example of ColorFeed, copied across almost all of it and re-built my code to revolve around this example but its just not triggering (I've come across someone else mentioning this also but there was no resolution on the thread). I know BGTaskScheduler is unreliable for the timeframes on which it refreshes, I only need it to update once a day so this isn't an issue. Kicking off Simulate background app refresh didn't do anything and I also left my phone overnight with the app loaded and it didn't fire.

I've redesigned my xcode project to use the App Delegate as the main entry point with @UIApplicationMain which means I can see my code works up to the applicationDidEnterBackground, but the background fetch tasks just aren't firing. The last print I get is "BGTask Scheduled" - And there are no errors.

Background Fetch and Background Processing are both enabled in Signing & Capabilities (both for troubleshooting). I have com.devname.AppName.refresh added to Permitted background task scheduler identifiers and BackgroundTasks has been imported.

I have tried the below with BGProcessingTaskRequest and BGAppRefreshTaskRequest. The pullData function takes less than 10 seconds so I was planning to use BGAppRefreshTaskRequest, the below has been attempted with BGAppProcessingTaskRequest also.

Here is my AppDelegate.

import SwiftUI
import UIKit
import Foundation
import BackgroundTasks


@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    var window: UIWindow?
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        
        let window = UIWindow()
                self.window = window
                window.rootViewController = UIHostingController(rootView: ContentView())
                window.makeKeyAndVisible()
         
        BGTaskScheduler.shared.register(forTaskWithIdentifier: "com.devname.AppName.refresh", using: nil) { task in
            self.handleAppRefresh(task: task as! BGProcessingTask)
        }
            return true
        }
            
    func applicationDidEnterBackground(_ application: UIApplication) {
        print("App Entered Background")
        scheduleAppRefresh()
    }
            
    func scheduleAppRefresh() {
        let request = BGProcessingTaskRequest(identifier: "com.devname.AppName.refresh")
        request.earliestBeginDate = Date(timeIntervalSinceNow: 1 * 60) // Fetch no earlier than 1 minutes from now
        
        do {
            try BGTaskScheduler.shared.submit(request)
            print("BGTask Scheduled")
        } catch {
            print("Could not schedule app refresh: \(error)")
        }
    }
    
    func handleAppRefresh(task: BGProcessingTask) {
        scheduleAppRefresh()
        print("BG Background Task fired")

        let queue = OperationQueue()
        queue.maxConcurrentOperationCount = 1
        print("Op Queue Set")

        let context = BlockOperation {
            print("Background Task Running")
//This is my function to perform in background task            
pullData()
        }
        queue.addOperation(context)
    }
}

Once I get a solution/this working I'll re-post my code as there seems to be a lack of working examples online for this function. Cheers!

UPDATE

---

So I've come across a couple of issues in the code that I have corrected (and edited original post.) Now when I simulate background refresh I'm getting errors which is good, I'm getting somewhere. I've stripped out the background task so that it literally just prints to console but I am still getting these errors. Does anyone have any ideas what could be causing this?

The 10.10.10.10 is my web hosting IP for where a CSV is hosted that will be called as part of the background task. Even when this is stripped out of the background task its still being referenced. None of the prints from the scheduled task are coming through either.

2022-02-25 17:17:27.746261+0000 APPNAME[11826:3148885] Connection 1: received failure notification

2022-02-25 17:17:27.746388+0000 APPNAME[11826:3148885] [connection] nw_flow_add_write_request [C1.1 10.10.10.10:443 failed channel-flow (satisfied (Path is satisfied), viable, interface: en0, ipv4, dns)] cannot accept write requests

2022-02-25 17:17:27.746452+0000 APPNAME[11826:3148885] [connection] nw_write_request_report [C1] Send failed with error "Socket is not connected"

Answer 1

Okay I'm not entirely sure this is 100% fixed as I'm still getting some errors but looks like the background tasks are running which is what this question is in relation to, the below is the some code that has background tasks running.

One thing I noticed: The "Simulate background refresh" in debug does not kick off a background refresh on either the simulator or my iphone. I just by chance left the app running in background on my iphone and noticed the print's appearing in the console. I'm not sure if this is an issue with my xcode or if I was doing something stupid but at least I've got the background tasks running.

I also get an error "[Framework] Task <BGProcessingTask: com.DEVNAME.APPNAME.refresh> dealloc'd without completing. This is a programmer error." - Not sure if this is an actual error, if I'm missing code or if it's just a warning but I'm seeing the prints from the scheduled task and its also run a test function I set up to schedule a notification.

Some of this code may be irrelevant but it's an example of background tasks working. - Hopefully it helps someone else in future since there are so little examples of this online. Cheers!

import SwiftUI
import UIKit
import Foundation
import BackgroundTasks


@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    var window: UIWindow?
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]?) -> Bool {
        
        let window = UIWindow()
        self.window = window
        window.rootViewController = UIHostingController(rootView: EventListView())
        window.makeKeyAndVisible()
        
        //code goes here
        
        BGTaskScheduler.shared.register(forTaskWithIdentifier: "com.devname.appname.refresh", using: DispatchQueue.main) { task in
            self.handleAppRefresh(task: task as! BGProcessingTask)
        }
        return true
    }
    
    func applicationDidEnterBackground(_ application: UIApplication) {
        print("App Entered Background")
        scheduleAppRefresh()
    }
    
    func scheduleAppRefresh() {
        let request = BGProcessingTaskRequest(identifier: "com.devname.appname.refresh")
        request.requiresNetworkConnectivity = true
        //request.earliestBeginDate = Date(timeIntervalSinceNow: 1 * 60) // Fetch no earlier than 15 minutes from now
        
        do {
            try BGTaskScheduler.shared.submit(request)
            print("BGTask Scheduled")
        } catch {
            print("Could not schedule app refresh: \(error)")
        }
    }
    func handleAppRefresh(task: BGProcessingTask) {
        //Scehdules a second refresh
        scheduleAppRefresh()
        BGNotification()
        print("BG Background Task fired")
}
}