How to set the initial view programmatically?

[cenisuru]

Hi, first off thanks for the great library.

I'm looking for some suggestions on how to implement this particular scenario. This is a quite common pattern. Say you have a LoginView and HomeView. If it's a brand new user, they land on the LoginView. If they've previously logged in, they are navigated directly to the HomeView. However, the first view of the stack still needs to be LoginView because if the user logs out, they need to be popped back to the LoginView but the user shouldn't see the LogInView when opening the app.

My current setup is this.

@main
struct NavigatorExpApp: App {
    var body: some Scene {
        WindowGroup {
            ManagedNavigationStack {
                LogInView()
                    .navigationDestination(Routes.self)
            }
            .environment(\.navigator, Navigator(configuration: configuration))
        }
    }
}

I modified it (this is a simplified version) to do the check in the initializer to see if the user is logged in and push to HomeView using the navigator.send() method.

@main
struct NavigatorExpApp: App {
    @Environment(\.navigator) var navigator: Navigator
    private let isLoggedIn: Bool = true
    
    init() {
        if isLoggedIn {
            navigator.send(Routes.home) // Accessing Environment<Navigator>'s value outside of being installed on a View. This will always read the default value and will not update.
        }
    }
    
    var body: some Scene {
        WindowGroup {
            ManagedNavigationStack {
                LogInView()
                    .navigationDestination(Routes.self)
            }
            .environment(\.navigator, Navigator(configuration: configuration))
            .onNavigationReceive { (route: Routes, navigator) in
                navigator.navigate(to: route)
                return .immediately
            }
        }
    }
}

But I'm getting the following error where I'm calling the send() method.

Accessing Environment's value outside of being installed on a View. This will always read the default value and will not update.

That probably be because I'm trying to access the navigator environment variable before it's injected into the view hierarchy.

I then tried to encapsulate everything with a ContainerView and move this checking logic one level down but I'm still getting the same error.

I'm not sure if I'm going about this the right way. Is there a better way to achieve this?

Any help is appreciated. Thank you.

[hmlongco]

I added some pause/resume sample code to main as I was fiddling with this, but honestly, I'm not sure that's a navigator problem. Why doesn't standard SwiftUI code work here?

@main
struct NavigatorExpApp: App {
    @Environment(\.navigator) var navigator: Navigator
    @State var isLoggedIn: Bool = true
    var body: some Scene {
        WindowGroup {
            ManagedNavigationStack {
                if isLoggedIn {
                    HomePageView()
                        .navigationDestination(Routes.self)
               } else {
                    LogInView()
                }
            }
            .environment(\.navigator, Navigator(configuration: configuration))
        }
    }
}

[cenisuru]

What I'm trying to do is a little different. I don't want to set a different initial view based on the logged in state. I'm trying to keep the same navigation stack and push the user to a view that is ahead in the stack based on the user's logged in status. Let me clarify.

New users open the app and they land on the LogInView. They enter the credentials and then pushed on to the HomeView.

For already logged in users, I want to directly push them onto the HomeView. But the navigation stack should still contain the LoginView as the initial view (even though the user may not see it upon launching the app).

This is because when/if the user logs out (say by tapping a button in the HomeView), I'm going to pop all views in the stack so they land back on the LoginView.

I was trying to achieve this when I came across the issue described in the original post.

[zzmasoud]

Hey all,
I was working on something similar, and keeping in mind that "this isn’t directly the navigator’s responsibility," I was able to achieve it like this:

Screen.Recording.2025-01-21.mov

import SwiftUI
import Navigator

public enum DummyDestinations: String, NavigationDestination {
    case a, b, c, z

    var iterator: Self {
        switch self {
        case .a:
            .b
        case .b:
            .c
        case .c:
            .z
        case .z:
            fatalError("this is the end!")
        }
    }

    public var view: some View {
        DummyView(destination: self)
    }
}

struct DummyView: View {
    @Environment(\.navigator) private var navigator
    let destination: DummyDestinations

    var body: some View {
        Form {
            if destination != .c {
                Button("go to the next page") {
                    navigator.push(destination.iterator)
                }
            } else {
                Button("back to root and change it with Z!") {
                    navigator.send(DummyDestinations.z)
                    navigator.popAll()
                }
            }
        }
        .navigationTitle(destination.rawValue.capitalized)
    }
}

public struct CoordinatorView: View {
    @Environment(\.navigator) private var navigator
    @State private var currentPage: DummyDestinations = .a

    public init() {}

    public var body: some View {
        Group {
            if currentPage == .z {
                Text("It's finally Z!")
            } else {
                DummyView(destination: .a)
                    .onNavigationReceive { (destination: DummyDestinations) in
                        if destination == .z {
                            currentPage = .z
                        }
                        return .immediately
                    }
            }
        }
        .navigationDestination(DummyDestinations.self)
    }
}

The main idea is the coordinator view, which simply switches views based on a condition. You’ll need to wrap it like this: ManagedNavigationStack { CoordinatorView() }
This way, we have a single ManagedNavigationStack and its corresponding Navigator!

But @hmlongco, have you ever thought of a better way to set the root view like we used to with UINavigationController? e.g. navigator.send(NavigationAction.setRoot(with: anotherView))
I believe what @cenisuru and I were trying to achieve (one of the requirements) was navigating back while the root view changes. I’m thinking it might not be possible because of NavigationPath. That brings me to 2 questions:

1. What’s your take on this?
2. Is it feasible by subclassing Navigator and defining my own action and modifiers?

P.S. The solution I shared does have some side effects! For example, if you have a navigation title, it will end up looking like this:

Screen.Recording.2025-01-21.with.Navigation.Title.mov

[hmlongco]

The biggest problem I have at the moment is that providing an initial navigation path interferes with navigation checkpoints.

[zzmasoud]

Like when we want to perform an internal action without notifying the delegate?