SwiftUI 中 NavigationView 导航栏的自定义后退按钮

Question

我想添加一个看起来像这样的自定义导航按钮：

现在，我已经为此编写了自定义 BackButton 视图。将该视图应用为领先的导航栏项目时，通过执行以下操作：

.navigationBarItems(leading: BackButton())

...导航视图如下所示：

我试过以下修饰符：

.navigationBarItem(title: Text(""), titleDisplayMode: .automatic, hidesBackButton: true)

运气不好。

问题

我怎样才能...

在导航栏中设置一个用作自定义后退按钮的视图？或者：
以编程方式将视图弹出回其父视图？
当采用这种方法时，我可以使用 .navigationBarHidden(true)

Answer 1

我发现了这个：https://ryanashcraft.me/swiftui-programmatic-navigation/

它确实有效，它可能为状态机控制显示内容奠定了基础，但它不像以前那么简单。

import Combine
import SwiftUI

struct DetailView: View {
    var onDismiss: () -> Void

    var body: some View {
        Button(
            "Here are details. Tap to go back.",
            action: self.onDismiss
        )
    }
}

struct RootView: View {
    var link: NavigationDestinationLink<DetailView>
    var publisher: AnyPublisher<Void, Never>

    init() {
        let publisher = PassthroughSubject<Void, Never>()
        self.link = NavigationDestinationLink(
            DetailView(onDismiss: { publisher.send() }),
            isDetail: false
        )
        self.publisher = publisher.eraseToAnyPublisher()
    }

    var body: some View {
        VStack {
            Button("I am root. Tap for more details.", action: {
                self.link.presented?.value = true
            })
        }
            .onReceive(publisher, perform: { _ in
                self.link.presented?.value = false
            })
    }
}

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

If you want to hide the button then you can replace the DetailView with this:

struct LocalDetailView: View {
    var onDismiss: () -> Void

    var body: some View {
        Button(
            "Here are details. Tap to go back.",
            action: self.onDismiss
        )
            .navigationBarItems(leading: Text(""))
    }
}

Answer 2

TL;DR

使用它来转换到你的观点：

NavigationLink(destination: SampleDetails()) {}

将此添加到视图本身：

@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

然后，在按钮操作或其他操作中，关闭视图：

presentationMode.wrappedValue.dismiss()

完整代码

来自 parent，使用 NavigationLink

导航

 NavigationLink(destination: SampleDetails()) {}

在 DetailsView 中隐藏 navigationBarBackButton 并将自定义后退按钮设置为前导 navigationBarItem、

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

    var btnBack : some View { Button(action: {
        self.presentationMode.wrappedValue.dismiss()
        }) {
            HStack {
            Image("ic_back") // set image here
                .aspectRatio(contentMode: .fit)
                .foregroundColor(.white)
                Text("Go back")
            }
        }
    }
    
    var body: some View {
            List {
                Text("sample code")
        }
        .navigationBarBackButtonHidden(true)
        .navigationBarItems(leading: btnBack)
    }
}

Answer 3

SwiftUI 1.0

看来您现在可以结合使用 navigationBarBackButtonHidden 和 .navigationBarItems 来获得您想要达到的效果。

代码

struct Navigation_CustomBackButton_Detail: View {
    @Environment(\.presentationMode) var presentationMode
    
    var body: some View {
        ZStack {
            Color("Theme3BackgroundColor")
            VStack(spacing: 25) {
                Image(systemName: "globe").font(.largeTitle)
                Text("NavigationView").font(.largeTitle)
                Text("Custom Back Button").foregroundColor(.gray)
                HStack {
                    Image("NavBarBackButtonHidden")
                    Image(systemName: "plus")
                    Image("NavBarItems")
                }
                Text("Hide the system back button and then use the navigation bar items modifier to add your own.")
                    .frame(maxWidth: .infinity)
                    .padding()
                    .background(Color("Theme3ForegroundColor"))
                    .foregroundColor(Color("Theme3BackgroundColor"))
                
                Spacer()
            }
            .font(.title)
            .padding(.top, 50)
        }
        .navigationBarTitle(Text("Detail View"), displayMode: .inline)
        .edgesIgnoringSafeArea(.bottom)
        // Hide the system back button
        .navigationBarBackButtonHidden(true)
        // Add your custom back button here
        .navigationBarItems(leading:
            Button(action: {
                self.presentationMode.wrappedValue.dismiss()
            }) {
                HStack {
                    Image(systemName: "arrow.left.circle")
                    Text("Go Back")
                }
        })
    }
}

例子

这是它的样子（摘自《SwiftUI Views》一书）：

Answer 4

根据此处的其他答案，这是选项 2 在 XCode 11.0 中为我工作的简化答案：

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

    var body: some View {

        Button(action: {
           self.presentationMode.wrappedValue.dismiss()
        }) {
            Image(systemName: "gobackward").padding()
        }
        .navigationBarHidden(true)

    }
}

注意：为了隐藏NavigationBar，我还需要在ContentView中设置然后隐藏NavigationBar。

struct ContentView: View {
    var body: some View {
        NavigationView {
            VStack {
                NavigationLink(destination: DetailView()) {
                    Text("Link").padding()
                }
            } // Main VStack
            .navigationBarTitle("Home")
            .navigationBarHidden(true)

        } //NavigationView
    }
}

Answer 5

我想你想在所有可导航屏幕中使用自定义后退按钮，所以我根据@Ashish 的回答编写了自定义包装器。

struct NavigationItemContainer<Content>: View where Content: View {
    private let content: () -> Content
    @Environment(\.presentationMode) var presentationMode

    private var btnBack : some View { Button(action: {
        self.presentationMode.wrappedValue.dismiss()
    }) {
        HStack {
            Image("back_icon") // set image here
                .aspectRatio(contentMode: .fit)
                .foregroundColor(.black)
            Text("Go back")
        }
        }
    }

    var body: some View {
        content()
            .navigationBarBackButtonHidden(true)
            .navigationBarItems(leading: btnBack)
    }

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content
    }
}

在 NavigationItemContainer 中包装屏幕内容：

用法：

struct CreateAccountScreenView: View {
    var body: some View {
        NavigationItemContainer {
            VStack(spacing: 21) {
                AppLogoView()
                //...
            }
        }
    }
}

Answer 6

我在这里看到的所有解决方案似乎都禁用了滑动返回功能以导航到上一页，因此分享一个我发现保持该功能的解决方案。您可以扩展根视图并覆盖导航样式并调用视图初始化程序中的函数。

示例视图

struct SampleRootView: View {

    init() {
        overrideNavigationAppearance()
    }

    var body: some View {
        Text("Hello, World!")
    }
}

分机

extension SampleRootView {
   func overrideNavigationAppearance() {
        let navigationBarAppearance = UINavigationBarAppearance()
        let barAppearace = UINavigationBar.appearance()
        barAppearace.tintColor = *desired UIColor for icon*
        barAppearace.barTintColor = *desired UIColor for icon*

        navigationBarAppearance.setBackIndicatorImage(*desired UIImage for custom icon*, transitionMaskImage: *desired UIImage for custom icon*)

        UINavigationBar.appearance().standardAppearance = navigationBarAppearance
        UINavigationBar.appearance().compactAppearance = navigationBarAppearance
        UINavigationBar.appearance().scrollEdgeAppearance = navigationBarAppearance
   }
}

这种方法的唯一不足是我还没有找到 remove/change 与自定义后退按钮关联的文本的方法。

Answer 7

这样不会禁用滑动。

适合我。 XCode11.3.1

将其放入您的根视图

init() {
    UINavigationBar.appearance().isUserInteractionEnabled = false
    UINavigationBar.appearance().backgroundColor = .clear
    UINavigationBar.appearance().barTintColor = .clear
    UINavigationBar.appearance().setBackgroundImage(UIImage(), for: .default)
    UINavigationBar.appearance().shadowImage = UIImage()
    UINavigationBar.appearance().tintColor = .clear
}

这在您的 child 视图中

@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

Button(action: {self.presentationMode.wrappedValue.dismiss()}) {
    Image(systemName: "gobackward")
}

Answer 8

此解决方案适用于 iPhone。但是，对于 iPad，由于 splitView，它无法工作。

import SwiftUI

struct NavigationBackButton: View {
  var title: Text?
  @Environment(\.presentationMode) private var presentationMode: Binding<PresentationMode>

  var body: some View {
    ZStack {
      VStack {
        ZStack {
          HStack {
            Button(action: {
              self.presentationMode.wrappedValue.dismiss()
            }) {
              Image(systemName: "chevron.left")
                .font(.title)
                .frame(width: 44, height: 44)
              title
            }
            Spacer()
          }
        }
        Spacer()
      }
    }
    .zIndex(1)
    .navigationBarTitle("")
    .navigationBarHidden(true)
  }
}

struct NavigationBackButton_Previews: PreviewProvider {
  static var previews: some View {
    NavigationBackButton()
  }
}

Answer 9

非常简单的方法。只有两行代码

@Environment(\.presentationMode) var presentationMode
self.presentationMode.wrappedValue.dismiss()

示例：

import SwiftUI

struct FirstView: View {
    @State var showSecondView = false
    
    var body: some View {
        NavigationLink(destination: SecondView(),isActive : self.$showSecondView){
            Text("Push to Second View")
        }
    }
}


struct SecondView : View{
    @Environment(\.presentationMode) var presentationMode

    var body : some View {    
        Button(action:{ self.presentationMode.wrappedValue.dismiss() }){
            Text("Go Back")    
        }    
    }
}

Answer 10

您可以为此使用 UIAppearance：

if let image = UIImage(named: "back-button") {
    UINavigationBar.appearance().backIndicatorImage = image
    UINavigationBar.appearance().backIndicatorTransitionMaskImage = image
}

这应该像 App.init 一样尽早添加到您的应用中。这也保留了本机向后滑动功能。

Answer 11

这是一个更简洁的版本，它使用其他评论中显示的原则来仅更改按钮的文本。 chevron.left 图标也可以轻松替换为其他图标。

创建您自己的按钮，然后使用 .navigationBarItems() 对其进行分配。我发现以下格式最接近默认后退按钮。

    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

    var backButton : some View {
        Button(action: {
            self.presentationMode.wrappedValue.dismiss()
        }) {
            HStack(spacing: 0) {
                Image(systemName: "chevron.left")
                    .font(.title2)
                Text("Cancel")
            }
        }
    }

确保使用 .navigationBarBackButtonHidden(true) 隐藏默认按钮并将其替换为您自己的按钮！

        List(series, id:\.self, selection: $selection) { series in
            Text(series.SeriesLabel)
        }
        .navigationBarBackButtonHidden(true)
        .navigationBarItems(leading: backButton)

Answer 12

就这么写：

import SwiftUI

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

        }.onAppear() {
            UINavigationBar.appearance().tintColor = .clear
            UINavigationBar.appearance().backIndicatorImage = UIImage(named: "back")?.withRenderingMode(.alwaysOriginal)
            UINavigationBar.appearance().backIndicatorTransitionMaskImage = UIImage(named: "back")?.withRenderingMode(.alwaysOriginal)
        }
    }
}

Answer 13

在 iOS 14+ 上使用 presentationMode 变量实际上非常容易

在此示例中，NewItemView 将在 addItem 完成时被解雇：

struct NewItemView: View {
    @State private var itemDescription:String = ""
    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
    
    
    var body: some View {
        VStack {
            TextEditor(text: $itemDescription)
        }.onTapGesture {
            hideKeyboard()
        }.toolbar {
            
            ToolbarItem {
                Button(action: addItem){
                    Text("Save")
                }
            }
            
        }.navigationTitle("Add Question")
        
    }
    private func addItem() {
        // Add save logic
        // ...
        
        // Dismiss on complete
        presentationMode.wrappedValue.dismiss()
    }
    
    private func hideKeyboard() {
        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
    }
}

struct NewItemView_Previews: PreviewProvider {
    static var previews: some View {
        NewItemView()
    }
}

如果您需要父（主）视图：

struct SampleMainView: View {
    @Environment(\.managedObjectContext) private var viewContext
    @FetchRequest(
        sortDescriptors: [NSSortDescriptor(keyPath: \DbQuestion.timestamp, ascending: true)],
        animation: .default)
    private var items: FetchedResults<Item>
    
    var body: some View {
        NavigationView {
            List {
                ForEach(items) { item in
                    NavigationLink {
                        Text("This is item detail page")
                    } label: {
                        Text("Item at \(item.id)")
                    }
                }
                
            }
            .toolbar {
                ToolbarItem {
                        // Creates a button on toolbar
                        NavigationLink {
                            // New Item Page
                            NewItemView()
                        } label: {
                            Text("Add item")
                        }
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    EditButton()
                }
            }.navigationTitle("Main Screen")
            
        }
    }
}

SwiftUI 中 NavigationView 导航栏的自定义后退按钮

Custom back button for NavigationView's navigation bar in SwiftUI

swift

navigationview

swiftui

问题

TL;DR

完整代码

SwiftUI 1.0

代码

例子