CODEWITHSUNDEEP
iosswiftbackground
matiastofteby
matiastofteby

Reputation: 431

Execution of background task before app enters to suspended state

I am trying to perform the Finite-Length background task in my app. However, as of now my code is not executed before the app is suspended.

I've followed quite a few tutorials that claims the following to be the way, but obviously I'm getting something wrong. Relevant code should be posted below (please just ask for any clarification if I'm missing something):

class Manager {

    private var backgroundTask: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid

    init(){
        // Add observer able of detecting when app will go to background
        NotificationCenter.default.addObserver(self, selector: #selector(self.didEnterBackground(_:)), name: .UIApplicationDidEnterBackground, object: nil)
    }

    deinit {
        // Observers removed when view controller is dismissed / deallocated
        NotificationCenter.default.removeObserver(self)
    }

       // Routine performed when app will resign from active
@objc private func didEnterBackground(_ notification: Notification){

    registerBackgroundTask()

    // Code that needs to be executed before app is suspended ------
    DispatchQueue.global().sync {

        self.isBackgrounding = true

        self.shutdownSession()


        self.isConnected = false
        self.isActivated = false
        self.activate = false

        self.connectionManager.closeConnectionToPeripherals()

    }
    // -----------------------------------------------------
    self.endBackgroundTask()

}

func registerBackgroundTask() {
    backgroundTask = UIApplication.shared.beginBackgroundTask { [weak self] in
        self?.endBackgroundTask()
    }
    assert(backgroundTask != UIBackgroundTaskInvalid)
}

func endBackgroundTask() {
    print("\n\n\nBackground task ended.\n\n\n")
    UIApplication.shared.endBackgroundTask(backgroundTask)
    backgroundTask = UIBackgroundTaskInvalid
}

}

I am facing a problem where the background task always seem to be ended before executing the code. How do I ensure that the code in my synchronous block gets executed before app is suspended?

I don't quite understand the "registerBackgroundTask()" either - even though the internet insists on implementing it this way - as it calls the endBackgroundTask().

Upvotes: 2

Views: 656

Answers (1)

ersjoh
ersjoh

Reputation: 331

You need to move your self.endBackgroundTask() call into your DispatchQueue block, right after self.connectionManager.closeConnectionToPeripherals().

The registerBackgroundTask method does not directly call self.endBackgroundTask(), instead it is only called if the background task expired. Usually, this happens if your app does not complete the task after ~30s in background.

Upvotes: 1

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