紧接着segue之后如何立即运行动画？

Question

I am running a slidein animation on an inner view of a new UIViewController which has been load. The problem is, because the animation can only be excecuted in ViewDidAppear() , that there is a delay between when the ViewController did load and when the animation starts. Because of this delay, it seems that the app has performance issues.

How can this problem be solved?

Answer 1

Use viewWillAppear should solve your problem.

The animation code should be asynchronously because inside of viewWillAppear the view hasn't appeared yet

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    DispatchQueue.main.async {
        self.appearanceAnimation()
    }
}

func appearanceAnimation() {
    //Add animaton here
}