trying to animate a constraint in swift

Question

I have a UITextField that I want to enlarge its width when tapped on. I set up the constraints and made sure the constraint on the left has the lower priority t

Answer 1

SWIFT 4.x :

self.mConstraint.constant = 100.0
UIView.animate(withDuration: 0.3) {
        self.view.layoutIfNeeded()
}

Example with completion:

self.mConstraint.constant = 100
UIView.animate(withDuration: 0.3, animations: {
        self.view.layoutIfNeeded()
    }, completion: {res in
        //Do something
})