StackState for overlay

[BaochengHan-TomTom]

Hi there,

I am exploring the possibility of applying StackState for an overlay in a view, similar to how stack-based screen navigation works. The goal is for the overlay, acting as a top panel on the main view, to dynamically transition based on the stack state.

Here is the example of domain code :

@Reducer
struct RootFeature {
    @Reducer
    struct Panel {
    case panel1(Panel1)
    case panel2(Panel2)
    case panel3(Panel3)
    case panel4(Panel4)
    case panel5(Panel5)
    }

    struct State {
        var panel = StackState<Panel.State>()
    }

    enum Action {
        case panel(StackActionOf<Panel>)
    }

    var body: some ReducerOf<Self> {
        Reduce { state, action in
            return .none
        }
        .forEach(\.panel, action: \.panel)
    }
}

what I want to have in UI is a view modifier overlayStack which accepts the panal store as a parameter and only show a view for the top state in StackState. Something like this:

struct RootView: View {
    @Bindable var store: StoreOf<RootFeature>
    var body: some View {
        BaseView()
            .overlayStack(path: $store.scope(state: \.panel, action: \.panel)) { store in
                switch store {
                case .panel1(let store):
                    Panel1View(store)
                case .panel2(let store):
                    Panel2View(store)
                case .panel3(let store):
                    Panel3View(store)
                case .panel4(let store):
                    Panel4View(store)
                case .panel5(let store):
                    Panel5View(store)
                }
        }
    }
}

I did looked the source code how

NavigationStack(
  path: // Store focused on StackState and StackAction
) {
  // Root view of the navigation stack
} destination: { store in
  // A view for each case of the Path.State enum
}

is implemented, but its implementation uses internal API that is not usable for me I believe.

Your help on how to implement the view modifier would be very much appreciated. Thanks.

[BaochengHan-TomTom]

The problem boils down to how to scope the top child store from of the StackState panel and StackAction panel ? Can anyone help here?