UIKit helpers generating UIAlertController from AlertState & ActionSheetState (#563)

* UIKit helpers generating UIAlertController from AlertState & ActionSheetState

* Exclude helpers from platforms not supporting UIKit (macOS)

* Exclude watchOS

* Update public API

* Update AlertStateUIKit.swift

Co-authored-by: Stephen Celis <[email protected]>

Author: 2 people

Sources/ComposableArchitecture/UIKit/AlertStateUIKit.swift

@@ -0,0 +1,110 @@
+#if canImport(UIKit) && !os(watchOS)
+import UIKit
+
+@available(iOS 13, *)
+@available(macCatalyst 13, *)
+@available(macOS, unavailable)
+@available(tvOS 13, *)
+@available(watchOS, unavailable)
+extension UIAlertController {
+  /// Creates a `UIAlertController` from `AlertState`.
+  ///
+  /// ```swift
+  /// class ParentViewController: UIViewController {
+  ///   let store: Store<ParentState, ParentAction>
+  ///   let viewStore: ViewStore<ViewState, ViewAction>
+  ///   private var cancellables: Set<AnyCancellable> = []
+  ///   private weak var alertController: UIAlertController?
+  ///   ...
+  ///   func viewDidLoad() {
+  ///     ...
+  ///     viewStore.publisher
+  ///       .settingsAlert
+  ///       .sink { [weak self] alert in
+  ///         guard let self = self else { return }
+  ///         if let alert = alert {
+  ///           let alertController = UIAlertController(state: alert, send: {
+  ///             self.viewStore.send(.settings($0))
+  ///           })
+  ///           self.present(alertController, animated: true, completion: nil)
+  ///           self.alertController = alertController
+  ///         } else {
+  ///           self.alertController?.dismiss(animated: true, completion: nil)
+  ///           self.alertController = nil
+  ///         }
+  ///       }
+  ///       .store(in: &cancellables)
+  ///   }
+  /// }
+  /// ```
+  ///
+  /// - Parameters:
+  ///   - state: The state of an alert that can be shown to the user.
+  ///   - send: A function that wraps an alert action in the view store's action type.
+  public convenience init<Action>(
+    state: AlertState<Action>,
+    send: @escaping (Action) -> Void
+  ) {
+    self.init(
+      title: String(state: state.title),
+      message: state.message.map { String(state: $0) },
+      preferredStyle: .alert)
+
+    if let primaryButton = state.primaryButton {
+      self.addAction(primaryButton.toUIAlertAction(send: send))
+    }
+
+    if let secondaryButton = state.secondaryButton {
+      self.addAction(secondaryButton.toUIAlertAction(send: send))
+    }
+  }
+  
+  /// Creates a `UIAlertController` from `ActionSheetState`.
+  ///
+  /// - Parameters:
+  ///   - state: The state of an action sheet that can be shown to the user.
+  ///   - send: A function that wraps a alert action in the view store's action type.
+  public convenience init<Action>(
+    state: ActionSheetState<Action>, send: @escaping (Action) -> Void
+  ) {
+    self.init(
+      title: String(state: state.title),
+      message: state.message.map { String(state: $0) },
+      preferredStyle: .actionSheet)
+
+    state.buttons.forEach { button in
+      self.addAction(button.toUIAlertAction(send: send))
+    }
+  }
+}
+
+@available(iOS 13, *)
+@available(macCatalyst 13, *)
+@available(macOS, unavailable)
+@available(tvOS 13, *)
+@available(watchOS, unavailable)
+extension AlertState.Button {
+  func toUIAlertAction(send: @escaping (Action) -> Void) -> UIAlertAction {
+    let action = {
+      switch self.action?.type {
+      case .none:
+        return
+      case let .some(.send(action)),
+        let .some(.animatedSend(action, animation: _)):  // Doesn't support animation in UIKit
+        send(action)
+      }
+    }
+    switch self.type {
+    case let .cancel(.some(title)):
+      return UIAlertAction(title: String(state: title), style: .cancel, handler: { _ in action() })
+    case .cancel(.none):
+      return UIAlertAction(title: nil, style: .cancel, handler: { _ in action() })
+    case let .default(title):
+      return UIAlertAction(title: String(state: title), style: .default, handler: { _ in action() })
+    case let .destructive(title):
+      return UIAlertAction(
+        title: String(state: title), style: .destructive, handler: { _ in action() })
+    }
+  }
+}
+#endif