UIView 自定义过渡在完成时快速返回

Question

我已经实现了 class BubbleAnimator，它应该在视图之间创建类似气泡的过渡，并通过 UIViewControllerTransitioningDelegate-协议添加它。演示动画到目前为止工作正常（这就是我没有为这部分添加所有代码的原因）。

但是在关闭视图时，'fromViewController' 在动画的最后闪烁 。在这个非常短的闪烁之后，正确的 toViewController 再次显示，但是这个故障非常烦人。以下是相关的animateTransition-方法：

    //Get all the necessary views from the context
    let containerView = transitionContext.containerView()
    let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
    let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)

    //Presenting
    if self.reverse == false {

        //Add the destinationvc as subview
        containerView!.addSubview(fromViewController!.view)
        containerView!.addSubview(toViewController!.view)

        /*...Animating the layer goes here... */

    //Dismissing
    } else {
        containerView!.addSubview(toViewController!.view)
        containerView!.addSubview(fromViewController!.view)

        //Init the paths
        let circleMaskPathInitial = UIBezierPath(ovalInRect: self.originFrame)
        let extremePoint = CGPoint(x: originFrame.origin.x , y: originFrame.origin.y - CGRectGetHeight(toViewController!.view.bounds) )
        let radius = sqrt((extremePoint.x*extremePoint.x) + (extremePoint.y*extremePoint.y))
        let circleMaskPathFinal = UIBezierPath(ovalInRect: CGRectInset(originFrame, -radius, -radius))

        //Create a layer
        let maskLayer = CAShapeLayer()
        maskLayer.path = circleMaskPathFinal.CGPath
        fromViewController!.view.layer.mask = maskLayer


        //Create and add the animation
        let animation = CABasicAnimation(keyPath: "path")
        animation.toValue = circleMaskPathInitial.CGPath
        animation.fromValue = circleMaskPathFinal.CGPath
        animation.duration = self.transitionDuration(transitionContext)
        animation.delegate = self
        maskLayer.addAnimation(animation, forKey: "path")
    }

清理发生在委托方法中：

override public func animationDidStop(anim: CAAnimation, finished flag: Bool) {
    self.transitionContext?.completeTransition(!(self.transitionContext?.transitionWasCancelled())!)
}

我想，我在将视图添加到 containerView 时做错了什么，但我无法弄清楚。另一种可能性是，当函数 completeTransition 被调用时，视图的图层蒙版被重置。

Answer 1

感谢this blogpost，我终于能够解决这个问题。简短说明：

CAAnimation只操作视图的表现层，不改变模型层。当动画现在结束时，它的值会恢复到模型层的原始值和未更改的值。

简短而简单的解决方法：

        animation.fillMode = kCAFillModeForwards
        animation.removedOnCompletion = false

更好的解决方案是在动画开始之前手动设置图层位置的最终值，因为它不会阻止动画被删除。这样，模型层就被赋予了正确的值：

        maskLayer.path = circleMaskPathInitial.CGPath
        //Create and add the animation below..

UIView 自定义过渡在完成时快速返回

UIView custom transition snaps back on completion

swift

animation

uiview

transition

caanimation