Is there a way to override dependency via store.scope/view init?

[atimca]

Hey all ✌️

At our company we're currently migrating a codebase to TCA. Because of the codebase is written with different approaches sometimes it's very hard to migrate small part to TCA without big rewrites.

At this particular moment I'm struggling with this.

There's a feature which depends on a previously built UIKit based router. This router opens other legacy UIKit based UIViewController's. Unfortunately, I cannot migrate navigation to the state base approach easily and use router as a dependency:

struct Router {
    var navigate: () -> Void
}

private enum RouterKey: DependencyKey {
   // 🚨There's nothing to put here as an implementation at the moment
    static let liveValue = Router(navigate: unimplemented())
}

extension DependencyValues {
    var router: Router {
        get { self[RouterKey.self] }
        set { self[RouterKey.self] = newValue }
    }
}

struct LeafFeature: ReducerProtocol {
    struct State: Equatable { }

    enum Action {
        case navigate
    }

    @Dependency(\.router) var router

    func reduce(into state: inout State, action: Action) -> EffectTask<Action> {
        switch action {
        case .navigate:
            router.navigate()
            return .none
        }
    }
}

struct LeafView: View {
    let store: StoreOf<LeafFeature>
}

This LeafFeature is a part of AppFeature:

struct AppFeature: ReducerProtocol {
    struct State: Equatable {
        var leaf: LeafFeature.State
    }

    enum Action {
        case leaf(LeafFeature.Action)
    }

    var body: some ReducerProtocol<State, Action> {
        // 🚨The latest place where I can override dependecies
        Scope(state: \.leaf, action: /Action.leaf) {
            LeafFeature()
        }
    }
}

LeafView is initialized in the old UIKit based controller

struct LegacyUIViewController {

    let store: StoreOf<AppFeature>

    var leafViewController: UIViewController {
        let navigationController = UINavigationController()
        // 🚨Somewhere here I'd like to inject navigationController.push function and use it inside rounter.navigate override
        let leafView = LeafView(
            store: store.scope(
                state: \.leaf,
                action: AppFeature.Action.leaf
            )
        )
        return UIHostingController(rootView: leafView)
    }
}

At the moment of initialization, I'd like to inject in this router navigationController.push function in one way or another and use it then inside router. However, I have access to this function only at the moment of the LeafView creation. The only one place for dependencies setup I've founded is inside body of AppFeature (at the moment of store creation). Thus, I don't have any instrument to override the dependency at the moment of view creation (at least I haven't founded one).

I tried to provide the simplified examples of what do we have right now in the code base. Very appreciate all the answers and thank you in advance!

[myihsan]

Injecting navigationController.push through an action seems a workaround for me, but it would be better if we can inject something during scoping.

[flopshot]

It would be nicer if navigation reduction with StackState and PresentationState had a middleware override to use our own logic with UINavigationController powering the auto-binding driven state navigation rather than SwiftUI navigation views

[flopshot]

That way, once we've fully migrated away from UIHostingController and use pure swiftui we could switch out our custom middleware and just use the Architecture default