SwiftUI：如何弹出到根视图

Question

最后，现在有了Beta
5，我们可以以编程方式弹出到父视图。但是，在我的应用程序中，有几个地方视图都有一个“保存”按钮，该按钮可以结束几个步骤并返回到开始。在UIKit中，我使用popToRootViewController（），但是我一直无法找到在SwiftUI中执行相同操作的方法。

以下是我尝试实现的模式的简单示例。有任何想法吗？

import SwiftUI

struct DetailViewB: View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
    var body: some View {
        VStack {
            Text("This is Detail View B.")

            Button(action: { self.presentationMode.value.dismiss() } )
            { Text("Pop to Detail View A.") }

            Button(action: { /* How to do equivalent to popToRootViewController() here?? */ } )
            { Text("Pop two levels to Master View.") }

        }
    }
}

struct DetailViewA: View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
    var body: some View {
        VStack {
            Text("This is Detail View A.")

            NavigationLink(destination: DetailViewB() )
            { Text("Push to Detail View B.") }

            Button(action: { self.presentationMode.value.dismiss() } )
            { Text("Pop one level to Master.") }
        }
    }
}

struct MasterView: View {
    var body: some View {
        VStack {
            Text("This is Master View.")

            NavigationLink(destination: DetailViewA() )
            { Text("Push to Detail View A.") }
        }
    }
}

struct ContentView: View {
    var body: some View {
        NavigationView {
            MasterView()
        }
    }
}

Answer 1

设置视图调节isDetailLink到false一个NavigationLink关键是让弹出到根的工作。isDetailLink是true默认设置，并且适用于包含的View。例如，在iPad横向上，分割视图是分开的，并isDetailLink确保目标视图将显示在右侧。因此，设置isDetailLink为false意味着目标视图将始终被推送到导航堆栈上。因此总是可以弹出。

连同设置isDetailLink为falseon
NavigationLink，将isActive绑定传递到每个后续的目标视图。最后，当您要弹出到根视图时，将该值设置为false，它将自动弹出所有内容：

import SwiftUI

struct ContentView: View {
    @State var isActive : Bool = false

    var body: some View {
        NavigationView {
            NavigationLink(
                destination: ContentView2(rootIsActive: self.$isActive),
                isActive: self.$isActive
            ) {
                Text("Hello, World!")
            }
            .isDetailLink(false)
            .navigationBarTitle("Root")
        }
    }
}

struct ContentView2: View {
    @Binding var rootIsActive : Bool

    var body: some View {
        NavigationLink(destination: ContentView3(shouldPopToRootView: self.$rootIsActive)) {
            Text("Hello, World #2!")
        }
        .isDetailLink(false)
        .navigationBarTitle("Two")
    }
}

struct ContentView3: View {
    @Binding var shouldPopToRootView : Bool

    var body: some View {
        VStack {
            Text("Hello, World #3!")
            Button (action: { self.shouldPopToRootView = false } ){
                Text("Pop to root")
            }
        }.navigationBarTitle("Three")
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}