Swift 使用选择环境对象弹出嵌套导航链接

Question

我有一个 NavigationView，它有 3 个我想依次导航到的视图。每个视图中都有一个 NavigationLink。理想情况下，我想要：

视图 1 -> 视图 2 -> 视图 3

但我得到的是：视图 1 -> 视图 2 -> 视图 3（1 秒） -> 视图 1

我正在为 NavigationLink 使用标记选择方法，并且选择来自 @Published EnvironmentObject.

代码如下：

import SwiftUI

struct ContentView: View {
    
    @EnvironmentObject var viewModel: ViewModel

    var body: some View {
        
        VStack {
            NavigationLink(destination: secondPage(), tag: "View 2", selection: $viewModel.selection) {
                Button(
                    action: {
                        viewModel.selection = "View 2"
                    }, label: {
                        Text("view 2")
                    }
                )
                .navigationTitle("View 1")
            }
            .isDetailLink(false)
        }
    }
}



struct secondPage: View {
    
    @EnvironmentObject var viewModel: ViewModel
    
    var body: some View {

        NavigationLink(destination: thirdPage(), tag: "View 3", selection: $viewModel.selection) {
            Button(
                action: {
                    viewModel.selection = "View 3"
                },
                label: {
                    Text("View 3")
                }
            )
            .navigationTitle("View 2")
        }
        .isDetailLink(false)
    }
}


struct thirdPage: View {
    
    var body: some View {
        VStack {
            Text("third page")
        }
        .navigationTitle("View 3")
    }
}

class ViewModel: ObservableObject {
    @Published var selection: String? = nil
}

import SwiftUI

@main
struct testApp: App {
    
    @StateObject var viewModel = ViewModel()
    
    var body: some Scene {
        WindowGroup {
            NavigationView {
                ContentView()
            }
            .navigationViewStyle(StackNavigationViewStyle())
            .environmentObject(viewModel)
        }
    }
}

我使用按钮和 viewModel，因为在我的实际代码中我需要代码来执行操作。

不胜感激！

Answer 1

欢迎使用 Whosebug！您遇到的问题与非常相似，但您使用的是不同的机制。弹回的原因是您使用相同的变量来处理两个 NavigationLinks，因此，而不是：

View 1 -> View 2 -> View 3

实际情况是：

View 1(viewModel.selection = "View 2") -> View 2

然后，当您再次尝试导航时：

View 2(viewModel.selection = "View 3")

你实际上是在把原来的link改成

View 1(viewModel.selection = "View 3") -> View 2

还有。 OS 变得混乱并返回到第一个 link(SecondPage)。要修复它，只需使用多个变量来保持导航状态：

struct ContentView: View {
    @EnvironmentObject var viewModel: PageViewModel

    var body: some View {
        
        VStack {
            NavigationLink(destination: secondPage(), tag: "View 2", selection: $viewModel.selection2) {
                Button(
                    action: {
                        viewModel.selection2 = "View 2"
                    }, label: {
                        Text("view 2")
                    }
                )
                .navigationTitle("View 1")
            }
            .isDetailLink(false)
        }
    }
}

struct secondPage: View {
    
    @EnvironmentObject var viewModel: PageViewModel
    
    var body: some View {

        NavigationLink(destination: thirdPage(), tag: "View 3", selection: $viewModel.selection3) {
            Button(
                action: {
                    viewModel.selection3 = "View 3"
                },
                label: {
                    Text("View 3")
                }
            )
            .navigationTitle("View 2")
        }
        .isDetailLink(false)
    }
}

struct thirdPage: View {
    
    var body: some View {
        VStack {
            Text("third page")
        }
        .navigationTitle("View 3")
    }
}

class PageViewModel: ObservableObject {
    @Published var selection2: String? = nil
    @Published var selection3: String? = nil
}

Swift 使用选择环境对象弹出嵌套导航链接

Swift Nested Navigation Links popping using selection Environment object

ios

swift

swiftui

navigationview

swiftui-navigationlink