检测 sheet 于 iOS 13 被驳回

Question

在iOS13之前，呈现的视图控制器用于覆盖整个屏幕。并且，当关闭时，父视图控制器 viewDidAppear 函数被执行。

现在 iOS 13 将默认将视图控制器显示为 sheet，这意味着卡片将部分覆盖底层视图控制器，这意味着 viewDidAppear 将不会被调用, 因为父视图控制器实际上从未消失过。

有没有办法检测到呈现的视图控制器sheet已被关闭？我可以在父视图控制器中覆盖其他一些功能 而不是使用某种委托?

Answer 1

Is there a way to detect that the presented view controller sheet was dismissed?

是的。

Some other function I can override in the parent view controller rather than using some sort of delegate?

没有。 "Some sort of delegate" 就是您的做法。让自己成为演示控制器的委托并覆盖 presentationControllerDidDismiss(_:).

https://developer.apple.com/documentation/uikit/uiadaptivepresentationcontrollerdelegate/3229889-presentationcontrollerdiddismiss

缺少一个通用的 runtime-generated 事件来通知您显示的视图控制器（无论是否全屏）已被关闭，这确实很麻烦；但这不是一个新问题，因为一直有 non-fullscreen 个呈现的视图控制器。只是现在（在iOS13）多了！我在别处用单独的 question-and-answer 来讨论这个话题：.

Answer 2

对于未来的读者，这里有一个更完整的实现答案：

在准备 segue 的根视图控制器中添加以下内容（假设您的模态有一个导航控制器）

    // Modal Dismiss iOS 13
    modalNavController.presentationController?.delegate = modalVc

在模态视图控制器中添加以下委托+方法

// MARK: - iOS 13 Modal (Swipe to Dismiss)

extension ModalViewController: UIAdaptivePresentationControllerDelegate {
    func presentationControllerDidAttemptToDismiss(_ presentationController: UIPresentationController) {


        print("slide to dismiss stopped")
        self.dismiss(animated: true, completion: nil)
    }
}

确保在模态视图控制器中以下属性为真，以便调用委托方法

    self.isModalInPresentation = true

利润

Answer 3

这是父视图控制器的代码示例，当子视图控制器呈现 作为 sheet（即在默认 iOS 13方式）被解雇：

public final class Parent: UIViewController, UIAdaptivePresentationControllerDelegate
{
  // This is assuming that the segue is a storyboard segue; 
  // if you're manually presenting, just set the delegate there.
  public override func prepare(for segue: UIStoryboardSegue, sender: Any?)
  {
    if segue.identifier == "mySegue" {
      segue.destination.presentationController?.delegate = self;
    }
  }

  public func presentationControllerDidDismiss(
    _ presentationController: UIPresentationController)
  {
    // Only called when the sheet is dismissed by DRAGGING.
    // You'll need something extra if you call .dismiss() on the child.
    // (I found that overriding dismiss in the child and calling
    // presentationController.delegate?.presentationControllerDidDismiss
    // works well).
  }
}

Jerland2 的回答很混乱，因为 (a) 最初的提问者想要在 sheet 被 dismissed 时获得函数调用（而他实现了 presentationControllerDidAttemptToDismiss，这是当用户尝试 并且失败 关闭 sheet 时调用），并且（b）设置 isModalInPresentation 是完全正交的，实际上将使呈现的 sheet 不可关闭（这与 OP 想要的相反）。

Answer 4

返回 viewWillAppear 和 viewDidAppear 的另一个选项已设置

let vc = UIViewController()
vc.modalPresentationStyle = .fullScreen

此选项覆盖全屏并在关闭后调用上述方法

Answer 5

调用presentingViewController.viewWillAppear不是很简单吗？在解雇之前？

self.presentingViewController?.viewWillAppear(false)
self.dismiss(animated: true, completion: nil)

Answer 6

以我的观点，苹果不应该设置pageSheet是默认的modalPresentationStyle

我想使用 swizzling

将 fullScreen 样式恢复为默认样式

像这样：

private func _swizzling(forClass: AnyClass, originalSelector: Selector, swizzledSelector: Selector) {
    if let originalMethod = class_getInstanceMethod(forClass, originalSelector),
       let swizzledMethod = class_getInstanceMethod(forClass, swizzledSelector) {
        method_exchangeImplementations(originalMethod, swizzledMethod)
    }
}

extension UIViewController {

    static func preventPageSheetPresentationStyle () {
        UIViewController.preventPageSheetPresentation
    }

    static let preventPageSheetPresentation: Void = {
        if #available(iOS 13, *) {
            _swizzling(forClass: UIViewController.self,
                       originalSelector: #selector(present(_: animated: completion:)),
                       swizzledSelector: #selector(_swizzledPresent(_: animated: completion:)))
        }
    }()

    @available(iOS 13.0, *)
    private func _swizzledPresent(_ viewControllerToPresent: UIViewController,
                                        animated flag: Bool,
                                        completion: (() -> Void)? = nil) {
        if viewControllerToPresent.modalPresentationStyle == .pageSheet
                   || viewControllerToPresent.modalPresentationStyle == .automatic {
            viewControllerToPresent.modalPresentationStyle = .fullScreen
        }
        _swizzledPresent(viewControllerToPresent, animated: flag, completion: completion)
    }
}

然后将此行放入您的 AppDelegate

UIViewController.preventPageSheetPresentationStyle()

Answer 7

拖动或调用 DISMISS FUNC 将适用于以下代码。

1) 在根视图控制器中，你告诉它哪个是它的展示视图控制器，如下代码

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "presenterID" {
        let navigationController = segue.destination as! UINavigationController
        if #available(iOS 13.0, *) {
            let controller = navigationController.topViewController as! presentationviewcontroller
            // Modal Dismiss iOS 13
            controller.presentationController?.delegate = self
        } else {
            // Fallback on earlier versions
        }
        navigationController.presentationController?.delegate = self

    }
}

2) 再次在根视图控制器中，告诉您当它的展示视图控制器被取消时您将做什么

public func presentationControllerDidDismiss(
  _ presentationController: UIPresentationController)
{
    print("presentationControllerDidDismiss")
}

1) 在演示视图控制器中，当您点击此图片中的取消或保存按钮时。下面的代码将是 called.The

self.dismiss(animated: true) {
        self.presentationController?.delegate?.presentationControllerDidDismiss?(self.presentationController!)
    }

Answer 8

覆盖 UIViewController 上的 viewWillDisappear 被关闭。它会通过 isBeingDismissed 布尔标志提醒您解雇。

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    if isBeingDismissed {
        print("user is dismissing the vc")
    }
}

** 如果用户在向下滑动卡片的中途再向上滑动卡片，即使卡片没有被关闭，它仍然会注册为被关闭。但这是您可能不关心的边缘情况。

Answer 9

Swift

在iOS13

中调用viewWillAppear的一般解决方案

class ViewController: UIViewController {

        override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            print("viewWillAppear")
        }

        //Show new viewController
        @IBAction func show(_ sender: Any) {
            let newViewController = NewViewController()
            //set delegate of UIAdaptivePresentationControllerDelegate to self
            newViewController.presentationController?.delegate = self
            present(newViewController, animated: true, completion: nil)
        }
    }

    extension UIViewController: UIAdaptivePresentationControllerDelegate {
        public func presentationControllerDidDismiss( _ presentationController: UIPresentationController) {
            if #available(iOS 13, *) {
                //Call viewWillAppear only in iOS 13
                viewWillAppear(true)
            }
        }
    }

Answer 10

如果您在全屏模式下使用 ModalPresentationStyle，控制器的行为将恢复正常。

ConsultarController controllerConsultar = this.Storyboard.InstantiateViewController("ConsultarController") as ConsultarController; controllerConsultar.ModalPresentationStyle = UIModalPresentationStyle.FullScreen; this.NavigationController.PushViewController(controllerConsultar, true);

Answer 11

如果有人无法访问呈现的视图控制器，他们可以在呈现视图控制器中重写以下方法并将 modalPresentationStyle 更改为 fullScreen 或者可以添加其中一种策略上面提到的这种方法

 override func present(_ viewControllerToPresent: UIViewController, animated flag: Bool, completion: (() -> Void)? = nil) {
    if let _ = viewControllerToPresent as? TargetVC {
        viewControllerToPresent.modalPresentationStyle = .fullScreen
    }
    super.present(viewControllerToPresent, animated: flag, completion: completion)
}

如果呈现的视图控制器是导航控制器，而您想检查根控制器，可以将上述条件更改为

if let _ = (viewControllerToPresent as? UINavigationController)?.viewControllers.first as? TargetVC {
   viewControllerToPresent.modalPresentationStyle = .fullScreen
}

Answer 12

如果您想在用户从 sheet 中关闭模式 sheet 时执行某些操作。假设您已经有一些带有 @IBAction 的关闭按钮和在关闭或执行其他操作之前显示警报的逻辑。您只想检测用户按下此类控制器的时刻。

方法如下：

class MyModalSheetViewController: UIViewController {

     override func viewDidLoad() {
        super.viewDidLoad()

        self.presentationController?.delegate = self
     }

     @IBAction func closeAction(_ sender: Any) {
         // your logic to decide to close or not, when to close, etc.
     }

}

extension MyModalSheetViewController: UIAdaptivePresentationControllerDelegate {

    func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {
        return false // <-prevents the modal sheet from being closed
    }

    func presentationControllerDidAttemptToDismiss(_ presentationController: UIPresentationController) {
        closeAction(self) // <- called after the modal sheet was prevented from being closed and leads to your own logic
    }
}

Answer 13

在 SwiftUI 中你可以使用 onDismiss 闭包

func sheet<Item, Content>(item: Binding<Item?>, onDismiss: (() -> Void)?, content: (Item) -> Content) -> some View

检测 sheet 于 iOS 13 被驳回

Detecting sheet was dismissed on iOS 13

uiviewcontroller

uikit

ios

swift

ios13