UIViewControllerAnimatedTransitioning动画首选内容大小

Question

假设我有一个UIViewControllerAnimatedTransitioning，显示为一个弹出框。在视图之间切换时，它的委托引用了一个自定义func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? { return AnimationController(presenting: (operation==.push) } 类：

class ViewController: UIViewController {

    ...

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.navigationController?.preferredContentSize = self.preferredContentSize
    }
    override func viewDidLoad() {
         super.viewDidLoad()
        self.navigationController?.preferredContentSize = self.preferredContentSize
    }
}

但是，推送的视图具有不同的首选内容大小：

preferedContentSize

当前，当我将视图控制器推到堆栈上时，我看到我的自定义动画已执行，然后更改了弹出窗口的大小。如何在动画运行的同时调整弹出窗口的大小？设置animateTransition(using: ...)或从func animateTransition(using transitionContext: UIViewControllerContextTransitioning) { guard let toView = transitionContext.view(forKey: .to) else { return } transitionContext.containerView.addSubview(toView) toView.alpha = 0.0 UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: { toView.alpha = 1.0 }) { _ in let success = !transitionContext.transitionWasCancelled if !success { toView.removeFromSuperview() } transitionContext.completeTransition(success) } } 内部调整约束似乎无效。

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