refactor(macos): adopt SwiftUI App lifecycle with NSViewRepresentable

Replace the AppKit-based AppDelegate template with a SwiftUI App that
hosts the React Native root view via NSViewRepresentable.

- Use @main on a SwiftUI App struct; remove main.swift
- Use Window scene with .defaultSize(1280x720) instead of manual NSWindow
- Wrap factory.rootViewFactory.view(withModuleName:) in NSViewRepresentable
- Drop the ~130 line NSMenu.standardMenu extension; SwiftUI provides the
  standard App, Edit, View, Window, and Help menus by default
- Initialize RCTReactNativeFactory in AppDelegate.init() instead of
  applicationDidFinishLaunching, so it's ready when the scene body evaluates

Reduces the template AppDelegate from 181 to 59 lines.

Author: Saadnajmi

packages/react-native/local-cli/generator-macos/templates/macos/HelloWorld-macOS/AppDelegate.swift

@@ -1,31 +1,32 @@
-import Cocoa
+import SwiftUI
 import React
 import React_RCTAppDelegate
 import ReactAppDependencyProvider
 
+@main
+struct HelloWorldApp: App {
+  @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
+
+  var body: some Scene {
+    Window("HelloWorld", id: "main") {
+      ReactNativeView(factory: appDelegate.reactNativeFactory)
+    }
+    .defaultSize(width: 1280, height: 720)
+  }
+}
+
+// MARK: - App Delegate
+
 class AppDelegate: NSObject, NSApplicationDelegate {
-  var window: NSWindow?
-  var reactNativeDelegate: ReactNativeDelegate?
-  var reactNativeFactory: RCTReactNativeFactory?
+  private let reactNativeDelegate: ReactNativeDelegate
+  let reactNativeFactory: RCTReactNativeFactory
 
-  func applicationDidFinishLaunching(_ notification: Notification) {
+  override init() {
     let delegate = ReactNativeDelegate()
-    let factory = RCTReactNativeFactory(delegate: delegate)
     delegate.dependencyProvider = RCTAppDependencyProvider()
-
     reactNativeDelegate = delegate
-    reactNativeFactory = factory
-
-    window = NSWindow(
-      contentRect: NSMakeRect(0, 0, 1280, 720),
-      styleMask: [.titled, .closable, .resizable, .miniaturizable],
-      backing: .buffered,
-      defer: false
-    )
-
-    NSApp.mainMenu = .standardMenu(appName: "HelloWorld")
-
-    factory.startReactNative(withModuleName: "HelloWorld", in: window)
+    reactNativeFactory = RCTReactNativeFactory(delegate: delegate)
+    super.init()
   }
 }
 
@@ -45,137 +46,14 @@ class ReactNativeDelegate: RCTDefaultReactNativeFactoryDelegate {
   }
 }
 
-// MARK: - Standard macOS Menu Bar
-
-extension NSMenu {
-  /// Creates a standard macOS menu bar with App, Edit, View, Window, and Help menus.
-  ///
-  /// This provides the default set of menu items that most macOS apps need, including
-  /// keyboard shortcuts for Quit (⌘Q), Close (⌘W), Copy (⌘C), Paste (⌘V), and others.
-  /// You can customize the returned menu by adding, removing, or modifying items.
-  static func standardMenu(appName: String) -> NSMenu {
-    let mainMenu = NSMenu()
-
-    mainMenu.addItem(appMenuItem(appName: appName))
-    mainMenu.addItem(editMenuItem())
-    mainMenu.addItem(viewMenuItem())
-    mainMenu.addItem(windowMenuItem())
-    mainMenu.addItem(helpMenuItem())
-
-    return mainMenu
-  }
-
-  // MARK: App Menu
-
-  private static func appMenuItem(appName: String) -> NSMenuItem {
-    let item = NSMenuItem()
-    let menu = NSMenu()
-
-    menu.addItem(title: "About \(appName)",
-                 action: #selector(NSApplication.orderFrontStandardAboutPanel(_:)))
-    menu.addItem(.separator())
-
-    let servicesMenu = NSMenu(title: "Services")
-    let servicesItem = NSMenuItem(title: "Services", action: nil, keyEquivalent: "")
-    servicesItem.submenu = servicesMenu
-    menu.addItem(servicesItem)
-    NSApp.servicesMenu = servicesMenu
-    menu.addItem(.separator())
-
-    menu.addItem(title: "Hide \(appName)",
-                 action: #selector(NSApplication.hide(_:)), key: "h")
-    menu.addItem(title: "Hide Others",
-                 action: #selector(NSApplication.hideOtherApplications(_:)),
-                 key: "h", modifiers: [.command, .option])
-    menu.addItem(title: "Show All",
-                 action: #selector(NSApplication.unhideAllApplications(_:)))
-    menu.addItem(.separator())
-    menu.addItem(title: "Quit \(appName)",
-                 action: #selector(NSApplication.terminate(_:)), key: "q")
-
-    item.submenu = menu
-    return item
-  }
-
-  // MARK: Edit Menu
-
-  private static func editMenuItem() -> NSMenuItem {
-    let item = NSMenuItem()
-    let menu = NSMenu(title: "Edit")
-
-    menu.addItem(title: "Undo", action: Selector(("undo:")), key: "z")
-    menu.addItem(title: "Redo", action: Selector(("redo:")), key: "Z")
-    menu.addItem(.separator())
-    menu.addItem(title: "Cut", action: #selector(NSText.cut(_:)), key: "x")
-    menu.addItem(title: "Copy", action: #selector(NSText.copy(_:)), key: "c")
-    menu.addItem(title: "Paste", action: #selector(NSText.paste(_:)), key: "v")
-    menu.addItem(title: "Paste and Match Style",
-                 action: #selector(NSTextView.pasteAsPlainText(_:)),
-                 key: "v", modifiers: [.command, .option])
-    menu.addItem(title: "Delete", action: #selector(NSText.delete(_:)))
-    menu.addItem(title: "Select All", action: #selector(NSText.selectAll(_:)), key: "a")
-
-    item.submenu = menu
-    return item
-  }
-
-  // MARK: View Menu
-
-  private static func viewMenuItem() -> NSMenuItem {
-    let item = NSMenuItem()
-    let menu = NSMenu(title: "View")
-
-    menu.addItem(title: "Enter Full Screen",
-                 action: #selector(NSWindow.toggleFullScreen(_:)),
-                 key: "f", modifiers: [.command, .control])
-
-    item.submenu = menu
-    return item
-  }
-
-  // MARK: Window Menu
-
-  private static func windowMenuItem() -> NSMenuItem {
-    let item = NSMenuItem()
-    let menu = NSMenu(title: "Window")
-
-    menu.addItem(title: "Close", action: #selector(NSWindow.performClose(_:)), key: "w")
-    menu.addItem(title: "Minimize", action: #selector(NSWindow.performMiniaturize(_:)), key: "m")
-    menu.addItem(title: "Zoom", action: #selector(NSWindow.performZoom(_:)))
-    menu.addItem(.separator())
-    menu.addItem(title: "Bring All to Front",
-                 action: #selector(NSApplication.arrangeInFront(_:)))
-
-    NSApp.windowsMenu = menu
-
-    item.submenu = menu
-    return item
-  }
-
-  // MARK: Help Menu
-
-  private static func helpMenuItem() -> NSMenuItem {
-    let item = NSMenuItem()
-    let menu = NSMenu(title: "Help")
+// MARK: - React Native SwiftUI View
 
-    NSApp.helpMenu = menu
+struct ReactNativeView: NSViewRepresentable {
+  let factory: RCTReactNativeFactory
 
-    item.submenu = menu
-    return item
+  func makeNSView(context: Context) -> NSView {
+    factory.rootViewFactory.view(withModuleName: "HelloWorld")
   }
 
-  // MARK: Convenience
-
-  /// Adds a menu item with an optional keyboard shortcut and modifier keys.
-  @discardableResult
-  fileprivate func addItem(
-    title: String,
-    action: Selector?,
-    key: String = "",
-    modifiers: NSEvent.ModifierFlags = .command
-  ) -> NSMenuItem {
-    let item = addItem(withTitle: title, action: action, keyEquivalent: key)
-    item.keyEquivalentModifierMask = modifiers
-    return item
-  }
+  func updateNSView(_ nsView: NSView, context: Context) {}
 }

packages/react-native/local-cli/generator-macos/templates/macos/HelloWorld-macOS/main.swift

@@ -9,15 +9,15 @@
 /* Begin PBXBuildFile section */
 		5142014D2437B4B30078DB4F /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5142014C2437B4B30078DB4F /* AppDelegate.swift */; };
 		514201522437B4B40078DB4F /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 514201512437B4B40078DB4F /* Assets.xcassets */; };
-		514201582437B4B40078DB4F /* main.swift in Sources */ = {isa = PBXBuildFile; fileRef = 514201572437B4B40078DB4F /* main.swift */; };
+
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
 		13B07F961A680F5B00A75B9A /* HelloWorld.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = HelloWorld.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		514201492437B4B30078DB4F /* HelloWorld.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = HelloWorld.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		5142014C2437B4B30078DB4F /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		514201512437B4B40078DB4F /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
-		514201572437B4B40078DB4F /* main.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = main.swift; sourceTree = "<group>"; };
+
 		514201562437B4B40078DB4F /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		514201592437B4B40078DB4F /* HelloWorld.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = HelloWorld.entitlements; sourceTree = "<group>"; };
 		ED297162215061F000B7C4FE /* JavaScriptCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = JavaScriptCore.framework; path = System/Library/Frameworks/JavaScriptCore.framework; sourceTree = SDKROOT; };
@@ -53,7 +53,7 @@
 			isa = PBXGroup;
 			children = (
 				5142014C2437B4B30078DB4F /* AppDelegate.swift */,
-				514201572437B4B40078DB4F /* main.swift */,
+
 				514201512437B4B40078DB4F /* Assets.xcassets */,
 				514201562437B4B40078DB4F /* Info.plist */,
 				514201592437B4B40078DB4F /* HelloWorld.entitlements */,
@@ -275,7 +275,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				514201582437B4B40078DB4F /* main.swift in Sources */,
+
 				5142014D2437B4B30078DB4F /* AppDelegate.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;