UIView.animate not work correctly in swift

Question

I Have a function that animates a view's y position. I call this function in tow ways, first as an action target for a button, second by observing a notification. In the first case it works, but in second case when it is called by notification it doesn't animate. the function code is:

func showResult() {
    resultMode = true

    self.containerView.frame.origin.y = CGFloat(1000)
    self.view.layoutIfNeeded()
    UIView.animate(
        withDuration: 3,
        animations: {
            self.containerView.frame.origin.y = CGFloat(200)
            self.view.layoutIfNeeded()
    } ,
        completion: nil
    )
}

it is called:

NotificationCenter.default.addObserver(self, selector: #selector(self.showResult), name: NSNotification.Name(rawValue: "SHOWRESULT"), object: nil)

and

resultBtn.addTarget(self, action: #selector(self.showResult), for: .touchUpInside)

Answer 1

Try triggering notification on main thread

    DispatchQueue.main.async {
        NotificationCenter.default.addObserver(self, selector: #selector(self.showResult), name: NSNotification.Name(rawValue: "SHOWRESULT"), object: nil)
    }

Reason:

Regular notification centers deliver notifications on the thread in which the notification was posted. Distributed notification centers deliver notifications on the main thread. At times, you may require notifications to be delivered on a particular thread that is determined by you instead of the notification center. For example, if an object running in a background thread is listening for notifications from the user interface, such as a window closing, you would like to receive the notifications in the background thread instead of the main thread. In these cases, you must capture the notifications as they are delivered on the default thread and redirect them to the appropriate thread.

Answer 2

Tr run modified below showResult method:

func showResult() {
    resultMode = true

    self.containerView.frame.origin.y = CGFloat(1000)
    self.view.layoutIfNeeded()
    DispatchQueue.main.async {
        UIView.animate(
            withDuration: 3,
            animations: {
                self.containerView.frame.origin.y = CGFloat(200)
                self.view.layoutIfNeeded()
            } ,
            completion: nil
        )
    }
}