自定义推送转换不起作用，而相同的自定义当前转换是

Posted 2023-03-16

【中文标题】自定义推送转换不起作用，而相同的自定义当前转换是

【英文标题】：Custom push transition isn't working whereas the same custom present transition is

【发布时间】：2016-08-22 11:39:01

【问题描述】：

我已经关注this tutorial 并观看了the WWDC video 关于这个主题的内容，但我找不到我的答案。

我的代码中有几乎相同的转换。当我将它作为呈现视图而不是作为推送视图时，它工作得很好。

它应该在弹出时将推送视图的快照从 CGRect 动画化到全屏，反之亦然。

这是我的UIViewControllerAnimatedTransitioning类的代码：

class ZoomingTransitionController: NSObject, UIViewControllerAnimatedTransitioning 

    let originFrame: CGRect
    let isDismissing: Bool

    init(originFrame: CGRect, isDismissing: Bool) 
        self.originFrame = originFrame
        self.isDismissing = isDismissing
    

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval 
        return Constant.Animation.VeryShort
    

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) 
        let containerView = transitionContext.containerView

        guard let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from),
            let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to) else 
                return
        

        let finalFrame = transitionContext.finalFrame(for: toVC)

        toVC.view.frame = finalFrame

        let snapshot = self.isDismissing ? fromVC.view.snapshotView(afterScreenUpdates: true) : toVC.view.snapshotView(afterScreenUpdates: true)
        snapshot?.frame = self.isDismissing ? finalFrame : self.originFrame
        snapshot?.layer.cornerRadius = Constant.FakeButton.CornerRadius
        snapshot?.layer.masksToBounds = true

        containerView.addSubview(toVC.view)
        containerView.addSubview(snapshot!)

        if self.isDismissing 
            fromVC.view.isHidden = true
         else 
            toVC.view.isHidden = true
        

        let duration = transitionDuration(using: transitionContext)

        UIView.animate(withDuration: duration,
                       animations: 
            snapshot?.frame = self.isDismissing ? self.originFrame : finalFrame
            ,
                       completion:  _ in
                        if self.isDismissing 
                            fromVC.view.isHidden = false
                         else 
                            toVC.view.isHidden = false
                        

                        snapshot?.removeFromSuperview()
                        transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        )
    

然后，我尝试使用两种方式展示一个新的视图控制器：呈现和推送。

我的FromViewController 是UINavigationControllerDelegate 和UIViewControllerTransitioningDelegate 的子类。

FromViewController 类呈现 ToViewController（工作正常）：

func buttonAction(_ sender: AnyObject) 
    self.tappedButtonFrame = sender.frame

    let toVC = self.storyboard!.instantiateViewController(withIdentifier: "ToViewController")
    toVC.transitioningDelegate = self

    self.present(toVC, animated: true, completion: nil)


func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? 
    let transitionController = ZoomingTransitionController(originFrame: self.tappedButtonFrame, isDismissing: false)

    return transitionController


func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? 
    let transitionController = ZoomingTransitionController(originFrame: self.tappedButtonFrame, isDismissing: true)

    return transitionController

FromViewController 类推送 ToViewController（不起作用）：

func buttonAction(_ sender: AnyObject) 
    self.tappedButtonFrame = sender.frame

    let toVC = self.storyboard!.instantiateViewController(withIdentifier: "ToViewController")

    self.navigationController?.pushViewController(toVC, animated: true)


func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? 
    switch operation 
    case .push:
        return ZoomingTransitionController(originFrame: self.tappedButtonFrame, isDismissing: false)

    case .pop:
        return ZoomingTransitionController(originFrame: self.tappedButtonFrame, isDismissing: true)

    default:
        return nil
    

推送时，委托方法被调用，ZoomingTransitionController 执行其代码正常（进入animateTransition 直到结束，没有明显问题）。但在屏幕上，任何时候都不会显示快照视图。 ToVC 在转换持续时间之后出现，但同时没有任何其他内容。

我不知道如何调试这个......你有什么想法吗？

谢谢！！

【问题讨论】：

你是否尝试过在 dispatchAsync 和主队列的帮助下推送它？

我做了，没有帮助。我认为问题出在我创建的快照上。

【参考方案1】：

我通过用toVC 的CGAffineTransform 替换快照元素（导致问题）找到了答案。

代码与here几乎相同。