DebugNavigationLinkView.swift

import SwiftUI
import ComposableArchitecture

struct DebugNavigationLinkView: View {
  
  struct ViewState: Equatable {
    var selectedNumber: Int?
  }
  
  enum ViewAction {
    case selectNumber(Int?)
  }
  
  static var reducer = Reducer<ViewState, ViewAction, Void> { state, action, environment in
    switch action {
    case .selectNumber(let number):
      state.selectedNumber = number
      return .none
    }
  }
  
  var store: Store<ViewState, ViewAction>

  var body: some View {
    NavigationView {
      WithViewStore(store) { viewStore in
        List {
          ForEach(1...4, id: \.self) { number in
            NavigationLink(
              destination: IfLetStore(
                self.store.scope(state: { $0.selectedNumber }).actionless,
                then: DebugNavigationLinkChildView.init(store:),
                else: Text("selectedNumber is nil!")
              ),
              tag: number,
              selection: viewStore.binding(get: { $0.selectedNumber }, send: {
                print("NavigationLink for \(number) is sending \($0)")
                return ViewAction.selectNumber($0)
              })
            ) {
              Text("Go to \(number)")
            }
          }
        }
      }
    }
  }
}

struct DebugNavigationLinkChildView: View {
  
  let store: Store<Int, Never>
  
  var body: some View {
    WithViewStore(store) { viewStore in
      Text("I am \(viewStore.state)")
    }
  }
}