can you run a background task in a notification service?

I have a push notification service (UNNotificationServiceExtension) that intercepts my push notifications to show rich push notifications. I tried to contact my server but I think the service is terminated before it runs all the code. I figured this out by the [modified] bit at the end not being there with my code and there without my code.

I've looked into silent notifications but I found out that that doesn't run when the user kills the app so that's no good.

Now I am thinking to do something along the lines of:

let queue = DispatchQueue.global(qos: .background) 
queue.async {
    self.contactServer()
}

It runs but the server is never contacted. So now I am not sure if the code works not? What do I do? How do I pass a task to the system to run it in the background because I think this service is too fast to actually wait for the server to be contacted. Sorry, I am new to swift and iOS in general.

Is there a way I can do something along the lines of:

await contactServer() 

NOTE: I know Swift doesn't have await but you get what I am trying to say here.

Here is my full code:

import UserNotifications
import ServerEngine
import UIKit

class NotificationService: UNNotificationServiceExtension {


var backgroundTask: UIBackgroundTaskIdentifier!
var contentHandler: ((UNNotificationContent) -> Void)?
var bestAttemptContent: UNMutableNotificationContent?

override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
    self.contentHandler = contentHandler
    bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)

    if let bestAttemptContent = bestAttemptContent {
        // Modify the notification content here...
        bestAttemptContent.title = "\(bestAttemptContent.title) [modified]"

        doBgTask()


        contentHandler(bestAttemptContent)
    }
}


func doBgTask() {
    let queue = DispatchQueue.global(qos: .background)
    queue.async {
        serverEngine.touchBase()
    }
}