SwiftUI:如何弹出到根视图 [英] SwiftUI: How to pop to Root view

问题描述

终于在 Beta 5 中，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，一个视图有一个保存"按钮，它可以结束一个多步骤的过程并返回到开头.在 UIKit 中，我使用 popToRootViewController()，但我一直无法找到在 SwiftUI 中执行相同操作的方法.

Finally now with Beta 5 we can programmatically pop to a parent View. However, there are several places in my App where a View has a "Save" button that concludes a several step process and returns to the beginning. In UIKit, I use popToRootViewController(), but I have been unable to figure out a way to do the same in SwiftUI.

下面是我试图实现的模式的一个简单示例.有什么想法吗?

Below is a simple example of the pattern I'm trying to achieve. Any ideas?

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()
        }
    }
}

推荐答案

在 NavigationLink 上将视图修饰符 isDetailLink 设置为 false 是让 pop-to-root 工作的关键.isDetailLink 默认为 true 并且适应包含视图.例如，在 iPad 横向上，拆分视图是分开的，并且 isDetailLink 确保目标视图将显示在右侧.因此，将 isDetailLink 设置为 false 意味着目标视图将始终被推送到导航堆栈上；因此可以随时弹出.

Setting the view modifier isDetailLink to false on a NavigationLink is the key to getting pop-to-root to work. isDetailLink is true by default and is adaptive to the containing View. On iPad landscape for example, a Split view is separated and isDetailLink ensures the destination view will be shown on the right-hand side. Setting isDetailLink to false consequently means that the destination view will always be pushed onto the navigation stack; thus can always be popped off.

在 NavigationLink 上将 isDetailLink 设置为 false 的同时，将 isActive 绑定传递到每个后续目标视图.最后当你想弹出到根视图时，将值设置为 false 它将自动弹出所有内容:

Along with setting isDetailLink to false on NavigationLink, pass the isActive binding to each subsequent destination view. At last when you want to pop to the root view, set the value to false and it will automatically pop everything off:

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()
    }
}

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