Add a Screen to Existing Feature

Guide for adding a new screen/view to an existing TCA feature with proper navigation.

Required Information

Ask the user for:

•Parent feature (e.g., ExploreRootFeature, MovieDetailsFeature)
•New screen name (e.g., MovieCredits, PersonFilmography)
•Navigation trigger (what action leads to this screen)

Steps

1. Create the New Feature Reducer

If the screen needs its own reducer, create it in the feature package:

swift

@Reducer
public struct {ScreenName}Feature: Sendable {
    @Dependency(\.{screenName}Client) private var client

    @ObservableState
    public struct State: Sendable {
        let id: Int
        var viewState: ViewState = .initial

        public init(id: Int) {
            self.id = id
        }
    }

    public enum ViewState: Sendable {
        case initial
        case loading
        case ready(ViewSnapshot)
        case error(Error)
    }

    public enum Action: Sendable {
        case didAppear
        case fetch
        case loaded(ViewSnapshot)
        case failed(Error)
        case navigate(Navigation)
    }

    public enum Navigation: Equatable, Hashable, Sendable {
        // Define navigation destinations
    }

    public init() {}

    public var body: some Reducer<State, Action> {
        Reduce { state, action in
            // Implementation
        }
    }
}

2. Add to Parent's Path Enum

In the parent feature's Path reducer enum:

swift

@Reducer
enum Path {
    case existingScreen(ExistingFeature)
    case {screenName}({ScreenName}Feature)  // Add this
}

3. Add Navigation Action Handling

In the parent reducer's body:

swift

case .existingScreen(.navigate(.{screenName}(let id))):
    state.path.append(.{screenName}({ScreenName}Feature.State(id: id)))
    return .none

Or if navigating from the root:

swift

case .{rootFeature}(.navigate(.{screenName}(let id))):
    state.path.append(.{screenName}({ScreenName}Feature.State(id: id)))
    return .none

4. Wire View in NavigationStack

In the parent's view, add to the destination closure:

swift

NavigationStack(path: $store.scope(state: \.path, action: \.path)) {
    RootView(store: store.scope(state: \.root, action: \.root))
} destination: { store in
    switch store.case {
    case .existingScreen(let store):
        ExistingView(store: store)
    case .{screenName}(let store):
        {ScreenName}View(store: store)  // Add this
    }
}

5. Create the View

swift

struct {ScreenName}View: View {
    @Bindable var store: StoreOf<{ScreenName}Feature>

    var body: some View {
        // View implementation
    }
}

Use SCREAMING_SNAKE_CASE keys for all user-facing strings. Build first, then add English values in Localizable.xcstrings — see SWIFTUI.md § Localization.

6. Add Navigation Enum Case to Source Feature

In the feature that triggers navigation:

swift

public enum Navigation: Equatable, Hashable, Sendable {
    case {screenName}(id: Int)
}

$ARGUMENTS