导致 UIViewControllerRepresentable 目标的多个 NavigationLinks 最终以空白屏幕结束

Question

我发现了一个存在错误的最小 SwiftUI 应用程序：

class HelloWorldVC: UIViewController {
    override func loadView() {
        super.loadView()
        let label = UILabel()
        label.text = "Hello, World"
        view.addSubview(label)

        label.translatesAutoresizingMaskIntoConstraints = false
        label.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
        label.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
        label.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
        label.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
    }
}

struct ViewControllerContainer: UIViewControllerRepresentable {
    let vc: UIViewController

    func makeUIViewController(context: Context) -> some UIViewController { vc }
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {}
}

struct ContentView: View {
    var body: some View {
        NavigationView {

            // Works:
            //NavigationLink("View UIKit VC", destination: ViewControllerContainer(vc: HelloWorldVC()))

            // Only loads the UIKit view once. It's blank on subsequent tries.
            NavigationLink(
                "Detail Screen",
                destination: NavigationLink(
                    "View UIKit VC",
                    destination: ViewControllerContainer(vc: HelloWorldVC())
                )
            )
        }
    }
}

重现步骤：

点击“详细信息屏幕”
点击“查看 UIKit VC”。您将看到“Hello, World”UIViewController。
点击返回
点击“查看 UIKit VC”

预期：

您应该再次看到“Hello, World”UIViewController

实际:

您将看到一个空白视图。只要您尝试，这种情况就会发生很多次。

注意：在注释掉的代码中，如果您只有一层深度的 NavigationLink，它可以正常工作。

Answer 1

您没有正确使用 UIViewControllerRepresentable。您需要在 makeUIViewController 中创建一个新的视图控制器，在您的案例中重复使用它会破坏视图控制器的生命周期。

UIViewControllerRepresentable 属性可以在创建或更新视图控制器时传递给它，如下所示：

struct ViewControllerContainer: UIViewControllerRepresentable {
    let props: Int

    func makeUIViewController(context: Context) -> some UIViewController { 
        HelloWorldVC(props: props) 
    }
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        uiViewController.props = props
    }
}

导致 UIViewControllerRepresentable 目标的多个 NavigationLinks 最终以空白屏幕结束

Multiple NavigationLinks leading to UIViewControllerRepresentable destination ends up with blank screen

swiftui

swiftui-navigationlink

uiviewcontrollerrepresentable

重现步骤：