Slow animation action

Question

Im have a nslayoutconstraint and when a user presses a button, the constraint is supposed to slowly reach zero. Currently it just automatically hits zero quickly when a button is pressed. My code isn't working. Here it is.

@IBAction func Expansion(_ sender: AnyObject) {

    UIView.animate(withDuration: 0.1, animations: {

        self.ScrolliewTopConstraint.constant = 0
        self.ScrollView.isScrollEnabled = true

    }, completion: nil)
}

Answer 1

You need to animate after setting the constant.

// set the constant
UIView.animate(withDuration: 0.1 {
   self.view.layoutIfNeeded()
}