I have two views:

1. Main view with Navigation link to User's settings page
2. User SettingsView, which allows to change user's settings (username)

struct User: Hashable {
    var id: Int
    var username: String
}

class Store: ObservableObject {
    @Published var user: User? = User(id: 1, username: "foo")

    func updateUser(to newUsername: String) {
        user?.username = newUsername
    }
}

@main
struct PlaygoundApp: App {
    @StateObject var store = Store()

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(store)
        }
    }
}

struct ContentView: View {
    @EnvironmentObject var store: Store

    var body: some View {
        NavigationView {
            VStack{
                Text("Username: \(store.user?.username ?? "")")

                NavigationLink(
                    destination: SettingsView(user: store.user),
                    label: {
                        Text("Edit user")
                    })
            }

        }
    }
}

struct SettingsView: View {
    @EnvironmentObject var store: Store

    var user: User?

    var body: some View {
        Text(user?.username ?? "")
        Button(action: {
            store.updateUser(to: "New username")
        }, label: {
            Text("Update username")
        })
    }
}

Here's how it works:

But I put NavigationLink button to Toolbar, each model change creates a new navigational view:

struct HomeView: View {
    @EnvironmentObject var store: Store

    var body: some View {
        VStack {
            Text("Home View")
            Text("Username: \(store.user?.username ?? "")")
        }
    }
}

struct ContentView: View {
    @EnvironmentObject var store: Store

    var body: some View {
        NavigationView {
            HomeView()
                .toolbar {
                    ToolbarItemGroup(placement: .navigationBarTrailing) {
                        if (store.user != nil) {
                            NavigationLink(
                                destination: SettingsView(user: store.user),
                                label: {
                                    Text("Edit user")
                                })
                        }
                    }
                }
        }
    }
}

Here's what happening:

How to aviod nested view creation?

Hi f1nnix,

Think I found the problem,

Remove var user: User? from the SettingView and change Text(store.user?.username ?? "")

so SettingView should be this.

struct SettingsView: View {
    @EnvironmentObject var store: Store

//    var user: User? \\  <- remove

    var body: some View {
        VStack {
            Text(store.user?.username ?? "")
            Button(action: {
                store.updateUser(to: "New username")
            }, label: {
                Text("Update username")
            })
        }
        .navigationTitle("Setting")
    }
}

PS you need to remove user from call as well.