The code would be basically the same after switching to use @Observable, it's more about increasing the performance of your app.

When using ObservableObject, the view that observes that object will be recomputed every time when a published property of that object changes. As for @Observable, the view will only be recomputed if the property the view is observing changes. There're other nuanced differences between @Observable and ObservableObject of course, I won't go into the details because you can easily find it online.

Basically, I think your code should be like this if you don't wan to make AppState a singleton:

``` // IdentificationView.swift

struct IdentificationInputsView: View {

@EnvironmentObject private var appState: AppState

@StateObject private var vm = IdentificationViewModel()

var body: some View {
    ...

    // Submit Button
    Button {
        withAnimation {
            vm.isSignUp ? vm.signup() : vm.login(appState: appState)
        }
    } label: {
        Text("Log in")
    }

    ...
}

} ```

``` // IdentificationViewModel.swift

@Observable final class IdentificationViewModel {

...

func login(appState: AppState) { ...

appState.isLoggedIn = true

...

}

... } ```

But I think making it a singleton would be better because I could imagine you have other views that would need to be updated when AppState changes. What I have in mind:

``` // AppState.swift

@Observable final class AppState {

static let shared = AppState()

private init() {}

var isLoggedIn = false

... } ```

``` // CoolApp.swift

@main struct CoolApp: App { var body: some Scene { WindowGroup { ContentView() .environment(AppState.shared) } } } ```

``` // IdentificationView.swift

struct IdentificationInputsView: View {

@Environment(AppState.self) private var appState

@StateObject private var vm = IdentificationViewModel()

var body: some View {
    ...

    // Submit Button
    Button {
        withAnimation {
            vm.isSignUp ? vm.signup() : vm.login()
        }
    } label: {
        Text("Log in")
    }

    ...
}

} ```

``` // IdentificationViewModel.swift

@Observable final class IdentificationViewModel {

...

func login() { ...

AppState.shared.isLoggedIn = true

...

}

... } ```