只有根級導航目的地對具有同質路徑的導航堆疊有效

我正在嘗試集成NavigationStack到我的應用程式中，SwiftUI我有四個視圖CealUIApp、OnBoardingView和。我想從用戶按下按鈕時導航到用戶按下按鈕時導航到UserTypeViewRegisterViewOnBoardingViewUserTypeViewOnBoardingViewUserTypeViewRegisterViewUserTypeView

下面是我的 CealUIApp 代碼

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

在OnBoardingView

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

在UserTypeView

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

當按下按鈕時，UserTypeView我一直在導航到UserTypeView而不是在日志中RegisterView使用 msg說XcodeOnly root-level navigation destinations are effective for a navigation stack with a homogeneous path.

uj5u.com熱心網友回復：

您可以Only root-level navigation destinations are effective for a navigation stack with a homogeneous path通過將路徑型別更改為NavigationPath.

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

但是隨后您會收到一條訊息/錯誤，我認為該訊息/錯誤可以更好地解釋該問題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 已決定掃描所有可用視圖的效率非常低，因此他們將navigationDestination優先使用 will。

試想一下，如果您OnBoardingView也可以選擇"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 如何選擇合適的？

那么如何“修復”呢？你可以試試這個替代方案。

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()
    }
}

標籤：IOS迅速迅捷

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