UIViewControllerAnimatedTransitioning 在动画进出视图时显示黑屏答案

【问题标题】：UIViewControllerAnimatedTransitioning shows a black screen when animating to and from viewUIViewControllerAnimatedTransitioning 在动画进出视图时显示黑屏
【发布时间】：2020-04-22 14:16:23
【问题描述】：

我正在尝试为我的视图控制器创建一个 easeInEaseOut 动画，但是，当我尝试为“to”和“from”视图设置动画时，“from”视图会变黑，直到动画完成。如果我只为“to”视图设置动画，那么新的视图控制器会正确设置动画，但会在“from”视图的顶部。我希望这两种观点一起移动，给人一种印象，即第一种正在滑落为第二种让路（我想被第二种推开更准确）。谁能告诉我为什么会这样？我尝试过多种设置，请参见下面的代码：

func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let toVC = transitionContext.viewController(forKey: .to), let fromVC = transitionContext.viewController(forKey: .from) else {
            dLog("No to or from VC")
            transitionContext.completeTransition(false)
            return
        }

        switch animationType {
        case .present:
            dLog("Present VC")
            transitionContext.containerView.addSubview(fromVC.view)
            transitionContext.containerView.addSubview(toVC.view)
            presentAnimation(with: transitionContext, fromView: fromVC.view, toView: toVC.view)
        case .dismiss:
            dLog("Dismiss VC")
        }
    }

    func presentAnimation(with transitionContext: UIViewControllerContextTransitioning, fromView: UIView, toView: UIView) {
        fromView.clipsToBounds = true
        toView.clipsToBounds = true
        fromView.transform = CGAffineTransform(translationX: 0, y: 0)
        toView.transform = CGAffineTransform(translationX: toView.frame.size.width, y: 0)

        let duration = transitionDuration(using: transitionContext)

        UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 0.0, initialSpringVelocity: 0.0, options: .curveEaseInOut, animations: {
            toView.transform = CGAffineTransform(translationX: 0.0,  y: 0.0)
            fromView.transform = CGAffineTransform(translationX: -fromView.frame.size.width, y: 0)
        }) { _ in
            transitionContext.completeTransition(true)
        }
    }

【问题讨论】：

标签： ios swift xcode uiviewcontroller uianimation

【解决方案1】：

如果其他人为此苦苦挣扎，我想通了。您必须改用 animateKeyFrames：

UIView.animateKeyframes(withDuration: duration, delay: 0.0, options: .calculationModeLinear, animations: {
            UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 2.0) {
                toView.transform = CGAffineTransform(translationX: 0, y: 0)
            }
            UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 2.0) {
                fromView.transform = CGAffineTransform(translationX: -fromView.frame.size.width, y: 0)
            }
        }) { _ in
            transitionContext.completeTransition(true)
        }

【讨论】：