CALayer Rotation动画在显示的ViewController上不起作用

Question

I have two view controllers (ie firstVC and secondVC). I am presenting secondVC over firstVC and trying to achieve rotation animation but it's not working, I have tried running animation on the main thread with some delay but it's giving weird behavior. Following is the code I am using to rotate the view.

extension UIView {

private static let kRotationAnimationKey = "rotationanimationkey"

func rotate(duration: Double = 1, delay: Int = 0) {
    if layer.animation(forKey: UIView.kRotationAnimationKey) == nil {
        let rotationAnimation = CABasicAnimation(keyPath: "transform.rotation")

        rotationAnimation.fromValue = 0.0
        rotationAnimation.toValue = Float.pi * 2.0
        rotationAnimation.duration = duration
        rotationAnimation.repeatCount = Float.infinity

        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(delay)) {
            self.layer.add(rotationAnimation, forKey: UIView.kRotationAnimationKey)
        }
    }
}

func stopRotating() {
    if layer.animation(forKey: UIView.kRotationAnimationKey) != nil {
        layer.removeAnimation(forKey: UIView.kRotationAnimationKey)
    }
}}

Note: By pushing 'secondVC' animation is working properly. But I wanted to present 'secondVC'.

I am not getting what's happening during the presentation of the view controller and rotation animation.

Please let me know if you find any solution.

Answer 1

For using custom presentation transition you have to confirm to UIViewControllerTransitioningDelegate . UIKit always call animationController(forPresented:presenting:source:) to see if a UIViewControllerAnimatedTransitioning is returned. If it is returning nil then default animation is used.