How to fix: UIView animations not restarting when returning to view controller

Question

I have a view that starts animating when a ViewController first opens. It works fine on initial launch, but when returning to the view after leaving the animation does not restart. The views are embedded in a Navigation controller

I tried placing the animation in several locations, including viewWillAppear, viewDidAppear and viewWillLayoutSubviews

I've placed a breakpoint in viewDidAppear and it does step through the code, but the animation does not restart.

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(true)
        UIView.animate(withDuration: 20.0, delay: 0, options: [.autoreverse, .repeat, .curveLinear], animations: {
            self.scrollingView.transform = CGAffineTransform(translationX: -350, y: 0)
        }, completion: nil)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(true)
        scrollingView.layer.removeAllAnimations()
    }

Answer 1

You need to return the scrollingView to its original position during the segue, because of the UINavigationController the 1st UIViewController does not go out of scope, aka it does not get instantiated again. Therefore when you come back to the 1st UIViewController, the scrollingView is still running the previous animation.

You need to restart the CGAffineTransform using the code below :

override func viewDidDisappear(_ animated: Bool) {
     self.textView.transform = CGAffineTransform.identity
}