TCA prerelease 1.0 NavigationLinkStore returningLastNonNilValue issue

ExampleApp.swift

import ComposableArchitecture
import SwiftUI

struct Parent: Reducer {
  struct State: Equatable {
    @PresentationState var child: Child.State?
  }

  enum Action: Equatable {
    case presentChildButtonTapped
    case dismissChildButtonTapped
    case child(PresentationAction<Child.Action>)
  }

  var body: some ReducerOf<Self> {
    Reduce { state, action in
      switch action {
      case .presentChildButtonTapped:
        state.child = Child.State()
        return .none

      case .dismissChildButtonTapped:
        state.child = nil
        return .none

      case .child(_):
        return .none
      }
    }
    .ifLet(\.$child, action: /Action.child) {
      Child()
    }
  }
}

struct Child: Reducer {
  struct State: Equatable {}

  enum Action: Equatable {
    case dismissButtonTapped
  }

  @Dependency(\.dismiss) var dismiss

  var body: some ReducerOf<Self> {
    Reduce { state, action in
      switch action {
      case .dismissButtonTapped:
        return .fireAndForget { await dismiss() }
      }
    }
  }
}

struct ParentView: View {
  let store: StoreOf<Parent>

  var body: some View {
    VStack {
      WithViewStore(store, observe: { $0.child != nil }) { viewStore in
        Text(viewStore.state ? "presented" : "dismissed")
      }

      NavigationLinkStore(
        store: store.scope(state: \.$child, action: Parent.Action.child),
        onTap: { ViewStore(store.stateless).send(.presentChildButtonTapped) },
        destination: ChildView.init
      ) {
        Text("Present child")
      }

      Button("Dismiss child") {
        ViewStore(store.stateless).send(.dismissChildButtonTapped)
      }
    }
    .buttonStyle(.borderedProminent)
    .navigationTitle("Parent")
  }
}

struct ChildView: View {
  let store: StoreOf<Child>

  var body: some View {
    Button("Dismiss") {
      ViewStore(store.stateless).send(.dismissButtonTapped)
    }
    .buttonStyle(.borderedProminent)
    .navigationTitle("Child")
  }
}

struct ExampleView: View {
  var body: some View {
    NavigationView {
      ParentView(store: Store(
        initialState: Parent.State(),
        reducer: Parent()
      ))

      Text("Placeholder")
    }
    .navigationViewStyle(.automatic)
  }
}

struct ExampleView_Previews: PreviewProvider {
  static var previews: some View {
    ExampleView()
  }
}

@main
struct ExampleApp: App {
  var body: some Scene {
    WindowGroup {
      ExampleView()
    }
  }
}