ios - 带有导航链接的 SwiftUI 消失后退按钮

Question

我有 3 个观点。其中一个有 NavigationView，第二个有 NavigationLink，最后一个只有工具栏的 child 。
所以当我在最后一个 View backButton 优雅中添加工具栏时，我的问题消失了。我该如何解决这个问题？
Screen recording of my problem

import SwiftUI

struct ContentView: View {
    var body: some View {
        NavigationView {
            VStack {
                Text("Hello, world!")
                    .padding()
                NavigationLink(destination: ListView()) {
                    
                    Image(systemName: "trash")
                        .font(.largeTitle)
                        .foregroundColor(.red)
                }
            }.navigationBarHidden(true)
            .navigationTitle("Image")
        }
    }
}

import SwiftUI

struct ListView: View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

    var body: some View {
        VStack {
            List {
                NavigationLink(destination: DetailView()) {
                    Text("Detail")
                }
            }
            
        }.navigationBarTitle(Text("Data"), displayMode: .large)
        .toolbar {
            Button("Save") {
                presentationMode.wrappedValue.dismiss()
            }
        }
    }
}

import SwiftUI

struct DetailView: View {
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
    var body: some View {
        
        VStack {
            Text("DetailView")
                .padding()
        }.navigationBarTitle(Text("Data"), displayMode: .large)
        .toolbar {
            Button("Save") {
                presentationMode.wrappedValue.dismiss()
            }
        }
    }
}

Answer 1

在控制台中，您会注意到此消息:

2021-04-27 12:37:36.862733-0700 MyApp[12739:255441] [Assert] displayModeButtonItem is internally managed and not exposed for DoubleColumn style. Returning an empty, disconnected UIBarButtonItem to fulfill the non-null contract.

NavigationView 的默认样式通常是 DefaultNavigationViewStyle , which is really just DoubleColumnNavigationViewStyle .使用 StackNavigationViewStyle相反，它按预期工作。
编辑:你说得对 StackNavigationViewStyle将打破 iPad 拆分 View 。但幸运的是， DoubleColumnNavigationViewStyle在 iPad 上工作正常，并且不会隐藏后退按钮。然后我们可以使用不同的 NavigationStyle取决于设备，如 this answer 中所示.

struct ResponsiveNavigationStyle: ViewModifier {
    @Environment(\.horizontalSizeClass) var horizontalSizeClass

    @ViewBuilder
    func body(content: Content) -> some View {
        if horizontalSizeClass == .compact { /// iPhone
            content.navigationViewStyle(StackNavigationViewStyle())
        } else { /// iPad or larger iPhone in landscape
            content.navigationViewStyle(DoubleColumnNavigationViewStyle())
        }
    }
}

struct ContentView: View {
    var body: some View {
        NavigationView {
            VStack {
                Text("Hello, world!")
                    .padding()
                NavigationLink(destination: ListView()) {
                    
                    Image(systemName: "trash")
                        .font(.largeTitle)
                        .foregroundColor(.red)
                }
            }
            .navigationBarHidden(true)
            .navigationTitle("Image")
        }
        .modifier(ResponsiveNavigationStyle()) /// here!
    }
}

结果:


iPad
苹果手机