how to stop a dispatchQueue in swift

问题

I have a DispatchQueue for a introViewController that shows a gif for 11 seconds and then display my login page... But also have a button that skip the intro and display the login. When I click it the time still running and when I am navigating in the app goes back to the login when the time ends.

this is my class

class GifClass: UIViewController {

@IBOutlet weak var gifImage: UIImageView!
@IBOutlet weak var skipButton: UIButton!


override func viewDidLoad() {
    super.viewDidLoad()

    gifImage.loadGif(name: "promed")

    DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(11)) {

        self.performSegue(withIdentifier: "introLogin", sender: self)
    }

}


@IBAction func skip(_ sender: Any) {


    performSegue(withIdentifier: "introLogin", sender: self)

}

}

how do I do to stop the time when I click the button?

回答1:

I'm not sure if there are best practices here, but I would consider doing what you are doing with a Timer rather than the DispatchQueue.

class GifClass: UIViewController {

    @IBOutlet weak var gifImage: UIImageView!
    @IBOutlet weak var skipButton: UIButton!

    var timer = Timer()

    override func viewDidLoad() {
        super.viewDidLoad()

        gifImage.loadGif(name: "promed")

        timer = Timer.scheduledTimer(timeInterval: 11, target: self, selector: #selector(timerAction), userInfo: nil, repeats: false)
    }

    @objc func timerAction() {
        performSegue(withIdentifier: "introLogin", sender: self)
    }

    @IBAction func skip(_ sender: Any) {
        timer.invalidate()
        performSegue(withIdentifier: "introLogin", sender: self)
    }
}

回答2:

For this, you can use a DispatchWorkItem. Here is the reference:

https://developer.apple.com/documentation/dispatch/dispatchworkitem

And here is an example of how you could use it in your code:

class GifClass: UIViewController {

    @IBOutlet weak var gifImage: UIImageView!
    @IBOutlet weak var skipButton: UIButton!

    private var workItem: DispatchWorkItem? // Create a private DispatchWorkItem property

    override func viewDidLoad() {
        super.viewDidLoad()

        gifImage.loadGif(name: "promed")

        workItem = DispatchWorkItem { // Set the work item with the block you want to execute
            self.performSegue(withIdentifier: "introLogin", sender: self)
        }
        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(11), execute: workItem!)
    }

    @IBAction func skip(_ sender: Any) {
        workItem?.cancel() // Cancel the work item in the queue so it doesn't run
        performSegue(withIdentifier: "introLogin", sender: self)    
    } 
}

回答3:

You don't stop the queue. Instead, when the task that you dispatched starts executing, it needs to check its context and do the right thing (often: nothing) if the context has changed.

来源：https://stackoverflow.com/questions/48016111/how-to-stop-a-dispatchqueue-in-swift

标签

swift

dispatch-queue