UiView.animateWithDuration 不为 Swift3 设置动画

Question

I am trying to animate all view outlets from bottom using below code (The outlets should come from bottom and fill the view within 1 seconds). However, it doesn't animate and everything is immediately shown no matter how much time I put. I noticed following:

• Duration is not respected
• Not even delay is respected

• Animation is not happening. Component is immediately shown

  override func viewDidAppear(_ animated: Bool) {

   super.viewDidAppear(animated); UIView.animate(withDuration: 1, animations: { self.topConstraint.constant = 0; self.imageView.frame.origin.y = 1024; self.view.setNeedsLayout(); })

Answer 1

I figured out the issue myself.

super.viewDidAppear(animated);

    UIView.animate(withDuration: 1, animations: {
        self.topConstraint.constant = 0;
        self.view.layoutIfNeeded()
        self.imageView.frame.origin.y = 1024;
        self.view.setNeedsLayout();
    })
    }

Answer 2

You need to remove self.imageView.frame.origin.y = 1024; , and set self.topConstraint.constant = 1024; before animation block