ios - 是否有 viewWillDisappear(_ :) or detect when a view is about to be removed? 的 SwiftUI 等效项

Question

在 SwiftUI 中，我试图找到一种方法，仅在使用默认的 navigationBackButton 时检测 View 即将被删除。然后执行一些操作。

使用 onDisappear(perform:) 的作用类似于 viewDidDisappear(_:)，并且该操作在另一个 View 出现后执行。

或者，我认为可以通过检测何时按下 default navigationBarBackButton 来解决上述问题。但我没有找到方法来检测这一点。

是否有任何解决方案可以在另一个 View 出现之前执行某些操作？

(我已经知道可以通过创建自定义导航后退按钮来关闭 View 来做到这一点)

Answer 1

这是适合我的方法，它不是纯 SwiftUI，但我认为值得发布

用法:

   SomeView()
   .onDisappear {
        print("x Default disappear")
    }
   .onWillDisappear { // << order does NOT matter
        print(">>> going to disappear")
    }

代码:

struct WillDisappearHandler: UIViewControllerRepresentable {
    func makeCoordinator() -> WillDisappearHandler.Coordinator {
        Coordinator(onWillDisappear: onWillDisappear)
    }

    let onWillDisappear: () -> Void

    func makeUIViewController(context: UIViewControllerRepresentableContext<WillDisappearHandler>) -> UIViewController {
        context.coordinator
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: UIViewControllerRepresentableContext<WillDisappearHandler>) {
    }

    typealias UIViewControllerType = UIViewController

    class Coordinator: UIViewController {
        let onWillDisappear: () -> Void

        init(onWillDisappear: @escaping () -> Void) {
            self.onWillDisappear = onWillDisappear
            super.init(nibName: nil, bundle: nil)
        }

        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }

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

struct WillDisappearModifier: ViewModifier {
    let callback: () -> Void

    func body(content: Content) -> some View {
        content
            .background(WillDisappearHandler(onWillDisappear: callback))
    }
}

extension View {
    func onWillDisappear(_ perform: @escaping () -> Void) -> some View {
        self.modifier(WillDisappearModifier(callback: perform))
    }
}