UIView - Animate with duration seems to ignore duration - ios

Question

I'm facing a problem : I have a very simple custom UIView which groups one UITextField and one UILabel.
The UILabel is on the UITextField, and I want that the UILabel go up to 40px when user begins to edit the UITextField.
I'm using constraints to set the textfield's frame and the label's frame.
So I just set the delegate in my custom view with UITextFieldDelegate protocol, and implement the delegate method : textFieldDidBeginEditing, as bellow :
I'm just animating the constraint (center Y) of my label in the delegate method.
func textFieldDidBeginEditing(textField: UITextField) {
self.centerVerticallyLabelConstraint.constant = -40
UIView.animateWithDuration(0.5) {
self.textFieldLabel.layoutIfNeeded()
}
}
What happens is that the UILabel goes up correctly, but it goes up instantly. It ignores the duration of 0.5 in my animation. I don't know why :
I'm not animating something else at the same time, I only have this animation.
I haven't disable animations for UIView.
The delegate is set to my UITextfield.
Any idea?

Answer 1

Try calling layoutIfNeeded on your view instead of textview.
UIView.animate(withDuration: 0.5) {
self.view.layoutIfNeeded()
}
Hope this helps.

Answer 2

need to call self.view.layoutIfNeeded() not self.textFieldLabel.layoutIfNeeded()
Thanks

Answer 3

Try Below code to execute:
func textFieldDidBeginEditing(textField: UITextField) {
UIView.animate(withDuration: 0.5) {
self.textFieldLabel.frame.origin.y -= 40
}
}

Answer 4

For me, the issue seems to be because I was already on the main thread & I called the animation block inside a GCD main.async call.
ie I had
DispatchQueue.main.async {
<# update the constraint s#>
self.animatedViewsParent.setNeedsLayout()
animatedView.setNeedsLayout()
UIView.animate(withDuration: 2.0) {
self.animatedViewsParent.layoutIfNeeded()
}
}
The view animates moves but does not animate gradually over 2.0 seconds. Removing the outer DispatchQueue.main.async {} solves the problem.