ios - 自定义 Segue 在显示目标 View Controller 之前将动画变为黑色

Question

我正在使用自定义 Segue 来在两个 View Controller 之间进行转换。这是我用于其中一个转换的转场:

class SegueFromRight: UIStoryboardSegue{
    override func perform() {
        // Assign the source and destination views to local variables.
        let src = self.source.view as UIView!
        let dst = self.destination.view as UIView!

        // Get the screen width and height.
        let screenWidth = UIScreen.main.bounds.size.width
        let screenHeight = UIScreen.main.bounds.size.height

        // Specify the initial position of the destination view.
        dst?.frame = CGRect(0.0, screenHeight, screenWidth, screenHeight)

        // Access the app's key window and insert the destination view above the current (source) one.
        let window = UIApplication.shared.keyWindow
        window?.insertSubview(dst!, aboveSubview: src!)

        // Animate the transition.
        UIView.animate(withDuration: 0.4, animations: { () -> Void in
            src?.frame = (src?.frame.offsetBy(dx: -screenWidth, dy: 0.0))!
            dst?.frame = (dst?.frame.offsetBy(dx: -screenWidth, dy: 0.0))!

        }) { (Finished) -> Void in
            self.source.present(self.destination as UIViewController,
                                                            animated: false,
                                                            completion: nil)
        }

    }
}

segue 工作得很好，但是动画不是我想要的。当它“插入”目标 View Controller 时，它会显示为黑色。它只会在动画完成后立即转向实际的 View Controller 。我想这是因为新的 View Controller 只有在动画完成后才会加载。但是我该如何预加载新的 View Controller ，以使动画看起来更流畅呢？ 展开转场不会显示黑色动画，因为目标 View Controller (之前的源 View Controller )当然已经加载。

Answer 1

这可能是您的问题dst?.frame = CGRect(0.0, screenHeight, screenWidth, screenHeight)。

试试这个dst?.frame = CGRect(screenWidth, 0.0, screenWidth, screenHeight)。

您的原始行将目标 View 设置为离开屏幕底部，而不是离开屏幕的右边缘。当您按屏幕宽度对 View 进行动画处理时，目标会从屏幕正下方滑动到下方和左侧。