UIView.animateWithDuration in viewDidAppear happens instantly

Question

Easy to reproduce:

• create a new app

• copy this code to your view controller that is being launched at start

  class ViewController: UIViewController {
  
      override func viewDidAppear(animated: Bool) {
          UIView.animateWithDuration(5,
              delay: 5,
              options: UIViewAnimationOptions.CurveEaseInOut,
              animations: {
  
              }, completion: { finished in
                  print("finished")
              }
          )
      }
  
  }
  

"finished" is logged instantly when I'd expect it to be logged 10 seconds after launch (5 from the animation duration + 5 from the delay).

How do I fix this?

The original problem I'm trying to solve is to presentViewController (with animated: false) before viewDidAppear, so that I can show the user a LoginViewControllerbefore the view for the controller in the back appears. But turns out that I can't call presentViewController in viewDidLoad or viewWillAppear.

So my workaround would be to set the LoginViewController's view's alpha to 0 and animate it to 1 (I know, it is a different effect, but it's better than calling presentViewController in viewDidAppear causing have the main controller to show and after a millisecond (not literally) have the LoginViewController's view appear).