UIViewControllerTransitioningDelegate 在呈现后立即被取消初始化答案

【问题标题】：UIViewControllerTransitioningDelegate being deinitialized immediately after it is presentedUIViewControllerTransitioningDelegate 在呈现后立即被取消初始化
【发布时间】：2026-01-18 16:45:01
【问题描述】：

我正在尝试使用UIPresentationController（和UIViewControllerTransitioningDelegate）以模态方式呈现带有自定义演示者的视图控制器。

问题在于在调用animationController(presented:presenting:source:) 后立即取消初始化转换委托。这意味着永远不会调用animationController(dismissed:) - 因此无法设置解除动画。

最后，我希望能够定义解雇动画。我相信我上面解释的是问题的根源，但在网上找不到任何相关信息。

这是我对UIViewControllerTransitioningDelegate的实现：

final class Manager: NSObject, UIViewControllerTransitioningDelegate {
    private let size: CGSize
    var animator: Animator

    init(size: CGSize) {
        self.size = size
        self.animator = Animator(duration: 0.4, loaf: loaf)
    }

    deinit {
        print("DEINIT") // 2) Then this is being called immediately after
    }

    func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
        return Controller(
            presentedViewController: presented,
            presenting: presenting,
            size: size
        )
    }

    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        animator.presenting = true
        return animator // 1) This is called first after the view controller is presented
    }

    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        animator.presenting = false
        return animator // 3) This is never called
    }
}

这就是我设置过渡委托的方式：

extension UIViewController {
    func presentModally(_ viewController: UIViewController, size: CGSize) {
        viewController.transitioningDelegate = Manager(size: size)
        viewController.modalPresentationStyle = .custom
        present(viewController, animated: true)
    }
}

当视图控制器被关闭时，视图总是默认被按下并消失。同样，animationController(dismissed:) 从未被调用，我不知道为什么。

【问题讨论】：

你需要一个强引用，因为 transitioningDelegate 属性很弱。
@maddy 强引用将保存在哪里？

标签： ios swift uiviewcontroller uipresentationcontroller

【解决方案1】：

我能够通过在呈现视图控制器上存储对UIViewControllerTransitioningDelegate 的引用来解决此问题。然后，在呈现模态时，将其设置为：

extension UIViewController {
    func presentModally(_ viewController: UIViewController, size: CGSize) {
        viewController.transDelegate = Manager(size: size)
        viewController.transitioningDelegate = viewController.transDelegate
        viewController.modalPresentationStyle = .custom
        present(viewController, animated: true)
    }
}

【讨论】：