NavigateAndLoad: Cancel loading on dismiss (#757)

* NavigateAndLoad: Cancel loading on dismiss

* Update Examples/CaseStudies/SwiftUICaseStudies/03-Navigation-NavigateAndLoad.swift

Co-authored-by: Stephen Celis <stephen.celis@gmail.com>

* Update Examples/CaseStudies/SwiftUICaseStudies/03-Navigation-Sheet-PresentAndLoad.swift

Co-authored-by: Stephen Celis <stephen.celis@gmail.com>

* Add cancellation to UIKitCaseStudies/NavigateAndLoad.swift

* Add cancellation to LoadThenNavigate studies

Co-authored-by: Stephen Celis <stephen.celis@gmail.com>

Examples/CaseStudies/UIKitCaseStudies/LoadThenNavigate.swift

@@ -9,6 +9,7 @@ struct LazyNavigationState: Equatable {
 }
 
 enum LazyNavigationAction: Equatable {
+  case onDisappear
   case optionalCounter(CounterAction)
   case setNavigation(isActive: Bool)
   case setNavigationIsActiveDelayCompleted
@@ -30,12 +31,16 @@ let lazyNavigationReducer =
     with: Reducer<
       LazyNavigationState, LazyNavigationAction, LazyNavigationEnvironment
     > { state, action, environment in
+      struct CancelId: Hashable {}
       switch action {
+      case .onDisappear:
+        return .cancel(id: CancelId())
       case .setNavigation(isActive: true):
         state.isActivityIndicatorHidden = false
         return Effect(value: .setNavigationIsActiveDelayCompleted)
           .delay(for: 1, scheduler: environment.mainQueue)
           .eraseToEffect()
+          .cancellable(id: CancelId())
       case .setNavigation(isActive: false):
         state.optionalCounter = nil
         return .none
@@ -120,6 +125,11 @@ class LazyNavigationViewController: UIViewController {
   @objc private func loadOptionalCounterTapped() {
     self.viewStore.send(.setNavigation(isActive: true))
   }
+
+  override func viewDidDisappear(_ animated: Bool) {
+    super.viewDidDisappear(animated)
+    self.viewStore.send(.onDisappear)
+  }
 }
 
 struct LazyNavigationViewController_Previews: PreviewProvider {