How to animate a UIView partially offscreen

Question

I have a rectangle UIView that sits at the bottom of its parent view (which is the full height and width of the screen) that I would like to animate down partially off of the screen after responding to an event. I have tried the following, but it just moves the origin up 100 and animates back to where it started:

UIView.animate(withDuration: 1.0, 
               delay: 1.2, 
               options: .curveEaseIn, 
               animations: {
                    self.subview.frame.origin.y += 100
                }, completion: {})

I've also tried setting a top constraint and changing that, but then it just squishes the view and it's children.

Answer 1

This are the outlets

    @IBOutlet weak var topConstraint: NSLayoutConstraint!
    @IBOutlet weak var testview: UIView!

Add this animation block where you want to animate on button action or user interaction.

self.topConstraint.constant += 100
    UIView.animate(withDuration: 5.0,
                   delay: 10,
                   options: .curveEaseIn,
                   animations: {
                    self.testview.layoutIfNeeded()
    }, completion: nil)