问SwiftUI NavigationView协调员问题

EN

class NavigationCoordinator: ObservableObject {
    
    @Published var showFirstDetailView: Bool = false
    @Published var showSecondDetailView: Bool = false
    @Published var showThirdDetailView: Bool = false
}

struct MainView: View {
  
    @StateObject
    var navigationCoordinator: NavigationCoordinator = NavigationCoordinator()

    var body: some View {
        
        NavigationView {
            VStack {
                Text("MainView").font(.headline)
                Text("showFirstDetailView: \(navigationCoordinator.showFirstDetailView.description)")
                NavigationLink(isActive: $navigationCoordinator.showFirstDetailView, destination: {FirstDetailView()}, label: {Text("Show FirstDetailView")})
            }
        }
        .environmentObject(navigationCoordinator)
    }
}

struct FirstDetailView: View {
    
    @EnvironmentObject
    var navigationCoordinator: NavigationCoordinator

    var body: some View {
        VStack {
            Text("FirstDetailView").font(.headline)
            Text("showSecondDetailView: \(navigationCoordinator.showSecondDetailView.description)")
            NavigationLink(isActive: $navigationCoordinator.showSecondDetailView, destination: {SecondDetailView()}, label: {Text("Show SecondDetailView")})
        }
    }
}

struct SecondDetailView: View {
    
    @EnvironmentObject
    var navigationCoordinator: NavigationCoordinator

    var body: some View {
        VStack {
            Text("SecondDetailView").font(.headline)
            Text("showThirdDetailView: \(navigationCoordinator.showThirdDetailView.description)")
            NavigationLink(isActive: $navigationCoordinator.showThirdDetailView, destination: {ThirdDetailView()}, label: {Text("Show ThirdDetailView")})
        }
    }
}

struct ThirdDetailView: View {
    
    @EnvironmentObject
    var navigationCoordinator: NavigationCoordinator
    
    var body: some View {
        Text("ThirdDetailView").font(.headline)
    }
}

struct MainView_Previews: PreviewProvider {
    static var previews: some View {
        MainView()
    }
}