只有根级导航目的地对于具有同质路径的导航堆栈有效

我正在尝试整合NavigationStack在我的 SwiftUI 应用程序中。

我有四个看法：CealUIApp, OnBoardingView, UserTypeView and RegisterView.

我想从OnBoardingView to UserTypeView当用户按下按钮时OnBoardingView.

并且，从UserTypeView to RegisterView当用户按下按钮时UserTypeView

下面是我的 CealUIApp 代码

@main
struct CealUIApp: App {
    
    @State private var path = [String]()
    
    var body: some Scene {
        WindowGroup {
            NavigationStack(path: $path){
                OnBoardingView(path: $path)
            }
        }
    }
}

In OnBoardingView

Button {
    path.append("UserTypeView")
}
label: {
    Text("Hello")
}
.navigationDestination(for: String.self) { string in
    UserTypeView(path: $path)
}

In UserTypeView

Button {
    path.append("RegisterView")
}
label: {
    Text("Hello")
}
.navigationDestination(for: String.self) { string in
    RegisterView()
}

当按钮打开时UserTypeView按下后，它会导航至UserTypeView代替RegisterView.

另外，Xcode 日志说

只有根级导航目的地对于具有同构路径的导航堆栈才有效。

你可以摆脱Only root-level navigation destinations are effective for a navigation stack with a homogeneous path通过将路径类型更改为NavigationPath.

@State private var path: NavigationPath = .init()

但随后您会收到一条消息/错误，我认为它更好地解释了问题A navigationDestination for “Swift.String” was declared earlier on the stack. Only the destination declared closest to the root view of the stack will be used.

Apple 认为扫描所有可用视图的效率非常低，因此他们将使用navigationDestination将优先。

试想一下，如果你的OnBoardingView还可以选择"RegisterView"

 .navigationDestination(for: String.self) { string in
        switch string{
        case "UserTypeView":
            UserTypeView(path: $path)
        case "RegisterView":
            Text("fakie register view")
        default:
            Text("No view has been set for \(string)")
        }
        
    }

SwiftUI 如何选择合适的呢？

那么如何“修复”呢？您可以尝试这个替代方案。

import SwiftUI

@available(iOS 16.0, *)
struct CealUIApp: View {
    @State private var path: NavigationPath = .init()
    var body: some View {
        NavigationStack(path: $path){
            OnBoardingView(path: $path)
                .navigationDestination(for: ViewOptions.self) { option in
                    option.view($path)
                }
        }
    }
    //Create an `enum` so you can define your options
    enum ViewOptions{
        case userTypeView
        case register
        //Assign each case with a `View`
        @ViewBuilder func view(_ path: Binding<NavigationPath>) -> some View{
            switch self{
            case .userTypeView:
                UserTypeView(path: path)
            case .register:
                RegisterView()
            }
        }
    }
}
@available(iOS 16.0, *)
struct OnBoardingView: View {
    @Binding var path: NavigationPath
    var body: some View {
        Button {
            //Append to the path the enum value
            path.append(CealUIApp.ViewOptions.userTypeView)
        } label: {
            Text("Hello")
        }
        
    }
}
@available(iOS 16.0, *)
struct UserTypeView: View {
    @Binding var path: NavigationPath
    var body: some View {
        Button {
            //Append to the path the enum value
            path.append(CealUIApp.ViewOptions.register)
        } label: {
            Text("Hello")
        }
        
    }
}
@available(iOS 16.0, *)
struct RegisterView: View {
    var body: some View {
        Text("Register")
        
    }
}
@available(iOS 16.0, *)
struct CealUIApp_Previews: PreviewProvider {
    static var previews: some View {
        CealUIApp()
    }
}