The Composable Architecture

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

Examples/CaseStudies/UIKitCaseStudies/Internal/IfLetStoreController.swift

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+import Combine
+import ComposableArchitecture
+import UIKit
+
+final class IfLetStoreController<State, Action>: UIViewController {
+  let store: Store<State?, Action>
+  let ifDestination: (Store<State, Action>) -> UIViewController
+  let elseDestination: () -> UIViewController
+
+  private var cancellables: Set<AnyCancellable> = []
+  private var viewController = UIViewController() {
+    willSet {
+      self.viewController.willMove(toParent: nil)
+      self.viewController.view.removeFromSuperview()
+      self.viewController.removeFromParent()
+      self.addChild(newValue)
+      self.view.addSubview(newValue.view)
+      newValue.didMove(toParent: self)
+    }
+  }
+
+  init(
+    store: Store<State?, Action>,
+    then ifDestination: @escaping (Store<State, Action>) -> UIViewController,
+    else elseDestination: @autoclosure @escaping () -> UIViewController
+  ) {
+    self.store = store
+    self.ifDestination = ifDestination
+    self.elseDestination = elseDestination
+    super.init(nibName: nil, bundle: nil)
+  }
+
+  required init?(coder: NSCoder) {
+    fatalError("init(coder:) has not been implemented")
+  }
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    self.store.ifLet(
+      then: { [weak self] store in
+        guard let self = self else { return }
+        self.viewController = self.ifDestination(store)
+      },
+      else: { [weak self] in
+        guard let self = self else { return }
+        self.viewController = self.elseDestination()
+      }
+    )
+    .store(in: &self.cancellables)
+  }
+}