How to set startDestination in Jetpack compose navigation

Question

@Composable
fun RootNav() {
    val navController = rememberNavController()
    val authViewModel: AuthViewModel = hiltViewModel()

    val authState by authViewModel.authState.collectAsState()
    val startDestination = when (authState) {
        is AuthState.Unauthenticated -> ScreenRoutes.AuthNav.route
        is AuthState.AuthenticatedWithoutCouple -> ScreenRoutes.RegisterNav.route
        is AuthState.AuthenticatedWithCouple -> ScreenRoutes.HomeNav.route
        else -> ScreenRoutes.AuthNav.route
    }
    NavHost(
        navController = navController,
        startDestination = startDestination
    ) {
        AuthNav(authViewModel, navController)

        RegisterNav(navController)

        composable(route = ScreenRoutes.HomeNav.route) {
            HomeNavGraph(navController){
                authViewModel.signOut()
            }
        }
    }
}

I have a structure like the one below, it works correctly but the user always sees the Login screen, how can I fix this?

Answer 1

You collected authState from AuthViewModel so I guest that your authState is initially set to AuthState.Unauthenticated in your AuthViewModel, something like:

val authState: MutableStateFlow<AuthState>(AuthState.Unauthenticated)

so your startDestination is always AuthState.Unauthenticated first before it's updated to any other value