feat(RCTAppDelegate): Implement RCTRootViewFactory (#42263)

Summary:
This PR implements `RCTRootViewFactory` a utility class (suggested by cipolleschi) that returns proper RCTRootView based on the current environment state (new arch/old arch/bridgeless). This class aims to preserve background compatibility by implementing a configuration class forwarding necessary class to RCTAppDelegate.

This PR leverages the `RCTRootViewFactory` in `RCTAppDelegate` for the default initialization of React Native (greenfield).

Here is an example of creating a Brownfield integration (without RCTAppDelegate) using this class (can be later added to docs):

1. Store reference to `rootViewFactory` and to `UIWindow`

`AppDelegate.h`:
```objc
interface AppDelegate : UIResponder <UIApplicationDelegate>

property(nonatomic, strong) UIWindow* window;
property(nonatomic, strong) RCTRootViewFactory* rootViewFactory;

end
```

2. Create an initial configuration using `RCTRootViewFactoryConfiguration` and initialize `RCTRootViewFactory` using it. Then you can use the factory to create a new `RCTRootView` without worrying about old arch/new arch/bridgeless.

 `AppDelegate.mm`
```objc
implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary<UIApplicationLaunchOptionsKey,id> *)launchOptions {

  // Create configuration
 RCTRootViewFactoryConfiguration *configuration = [[RCTRootViewFactoryConfiguration alloc] initWithBundleURL:self.bundleURL
                                                                                                 newArchEnabled:self.fabricEnabled
                                                                                             turboModuleEnabled:self.turboModuleEnabled
                                                                                              bridgelessEnabled:self.bridgelessEnabled];

  // Initialize RCTRootViewFactory
  self.rootViewFactory = [[RCTRootViewFactory alloc] initWithConfiguration:configuration];

  // Create main root view
  UIView *rootView = [self.rootViewFactory viewWithModuleName:@"RNTesterApp" initialProperties:@{} launchOptions:launchOptions];

  // Set main window as you prefer for your Brownfield integration.
  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  UIViewController *rootViewController = [UIViewController new];
  rootViewController.view = rootView;
  self.window.rootViewController = rootViewController;
  [self.window makeKeyAndVisible];

  // Later in the codebase you can initialize more rootView's using rootViewFactory.

  return YES;
}
end
```
bypass-github-export-checks

[INTERNAL] [ADDED] - Implement RCTRootViewFactory

Pull Request resolved: #42263

Test Plan: Check if root view is properly created on app initialization

Reviewed By: dmytrorykun

Differential Revision: D53179625

Pulled By: cipolleschi

fbshipit-source-id: 9bc850965ba30d84ad3e67d91dd888f0547c2136

packages/react-native/Libraries/AppDelegate/RCTAppDelegate.h

@@ -7,6 +7,7 @@
 
 #import <React/RCTBridgeDelegate.h>
 #import <UIKit/UIKit.h>
+#import "RCTRootViewFactory.h"
 
 @class RCTBridge;
 @protocol RCTBridgeDelegate;
@@ -57,9 +58,12 @@ NS_ASSUME_NONNULL_BEGIN
 
 /// The window object, used to render the UViewControllers
 @property (nonatomic, strong, nonnull) UIWindow *window;
-@property (nonatomic, strong, nullable) RCTBridge *bridge;
+@property (nonatomic, nullable) RCTBridge *bridge;
 @property (nonatomic, strong, nullable) NSString *moduleName;
 @property (nonatomic, strong, nullable) NSDictionary *initialProps;
+@property (nonatomic, strong, nonnull) RCTRootViewFactory *rootViewFactory;
+
+@property (nonatomic, nullable) RCTSurfacePresenterBridgeAdapter *bridgeAdapter;
 
 /**
  * It creates a `RCTBridge` using a delegate and some launch options.
@@ -126,13 +130,6 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)setRootView:(UIView *)rootView toRootViewController:(UIViewController *)rootViewController;
 
-/// This method controls whether the App will use RuntimeScheduler. Only applicable in the legacy architecture.
-///
-/// @return: `YES` to use RuntimeScheduler, `NO` to use JavaScript scheduler. The default value is `YES`.
-- (BOOL)runtimeSchedulerEnabled;
-
-@property (nonatomic, strong) RCTSurfacePresenterBridgeAdapter *bridgeAdapter;
-
 /// This method returns a map of Component Descriptors and Components classes that needs to be registered in the
 /// new renderer. The Component Descriptor is a string which represent the name used in JS to refer to the native
 /// component. The default implementation returns an empty dictionary. Subclasses can override this method to register

packages/react-native/Libraries/AppDelegate/RCTAppDelegate.mm

@@ -39,85 +39,28 @@
 #import <react/renderer/runtimescheduler/RuntimeSchedulerCallInvoker.h>
 #import <react/runtime/JSRuntimeFactory.h>
 
-@interface RCTAppDelegate () <
-    RCTTurboModuleManagerDelegate,
-    RCTComponentViewFactoryComponentProvider,
-    RCTContextContainerHandling> {
-  std::shared_ptr<const facebook::react::ReactNativeConfig> _reactNativeConfig;
-  facebook::react::ContextContainer::Shared _contextContainer;
-}
+@interface RCTAppDelegate () <RCTComponentViewFactoryComponentProvider, RCTTurboModuleManagerDelegate>
 @end
 
-static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabricEnabled)
-{
-  NSMutableDictionary *mutableProps = [initialProps mutableCopy] ?: [NSMutableDictionary new];
-  return mutableProps;
-}
-
-@interface RCTAppDelegate () <RCTCxxBridgeDelegate> {
-  std::shared_ptr<facebook::react::RuntimeScheduler> _runtimeScheduler;
-}
-@end
-
-@implementation RCTAppDelegate {
-  RCTHost *_reactHost;
-}
-
-- (instancetype)init
-{
-  if (self = [super init]) {
-    _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
-    _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
-    _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
-  }
-  return self;
-}
+@implementation RCTAppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
   RCTSetNewArchEnabled([self newArchEnabled]);
-  BOOL enableTM = self.turboModuleEnabled;
-  BOOL fabricEnabled = self.fabricEnabled;
-  BOOL enableBridgeless = self.bridgelessEnabled;
-
-  NSDictionary *initProps = updateInitialProps([self prepareInitialProps], fabricEnabled);
+  RCTAppSetupPrepareApp(application, self.turboModuleEnabled);
 
-  RCTAppSetupPrepareApp(application, enableTM);
+  self.rootViewFactory = [self createRCTRootViewFactory];
 
-  UIView *rootView;
-  if (enableBridgeless) {
-    // Enable native view config interop only if both bridgeless mode and Fabric is enabled.
-    RCTSetUseNativeViewConfigsInBridgelessMode(fabricEnabled);
+  UIView *rootView = [self.rootViewFactory viewWithModuleName:self.moduleName
+                                            initialProperties:self.initialProps
+                                                launchOptions:launchOptions];
 
-    // Enable TurboModule interop by default in Bridgeless mode
-    RCTEnableTurboModuleInterop(YES);
-    RCTEnableTurboModuleInteropBridgeProxy(YES);
-
-    [self createReactHost];
+  if (self.newArchEnabled || self.fabricEnabled) {
     [RCTComponentViewFactory currentComponentViewFactory].thirdPartyFabricComponentsProvider = self;
-    RCTFabricSurface *surface = [_reactHost createSurfaceWithModuleName:self.moduleName initialProperties:initProps];
-
-    RCTSurfaceHostingProxyRootView *surfaceHostingProxyRootView = [[RCTSurfaceHostingProxyRootView alloc]
-        initWithSurface:surface
-        sizeMeasureMode:RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightExact];
-
-    rootView = (RCTRootView *)surfaceHostingProxyRootView;
-    rootView.backgroundColor = [UIColor systemBackgroundColor];
-  } else {
-    if (!self.bridge) {
-      self.bridge = [self createBridgeWithDelegate:self launchOptions:launchOptions];
-    }
-    if ([self newArchEnabled]) {
-      self.bridgeAdapter = [[RCTSurfacePresenterBridgeAdapter alloc] initWithBridge:self.bridge
-                                                                   contextContainer:_contextContainer];
-      self.bridge.surfacePresenter = self.bridgeAdapter.surfacePresenter;
-
-      [RCTComponentViewFactory currentComponentViewFactory].thirdPartyFabricComponentsProvider = self;
-    }
-    rootView = [self createRootViewWithBridge:self.bridge moduleName:self.moduleName initProps:initProps];
   }
   [self _logWarnIfCreateRootViewWithBridgeIsOverridden];
   [self customizeRootView:(RCTRootView *)rootView];
+
   self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
   UIViewController *rootViewController = [self createRootViewController];
   [self setRootView:rootView toRootViewController:rootViewController];
@@ -140,21 +83,11 @@ - (NSURL *)sourceURLForBridge:(RCTBridge *)bridge
   return nil;
 }
 
-- (NSDictionary *)prepareInitialProps
-{
-  return self.initialProps;
-}
-
 - (RCTBridge *)createBridgeWithDelegate:(id<RCTBridgeDelegate>)delegate launchOptions:(NSDictionary *)launchOptions
 {
   return [[RCTBridge alloc] initWithDelegate:delegate launchOptions:launchOptions];
 }
 
-- (void)customizeRootView:(RCTRootView *)rootView
-{
-  // Override point for customization after application launch.
-}
-
 - (UIView *)createRootViewWithBridge:(RCTBridge *)bridge
                           moduleName:(NSString *)moduleName
                            initProps:(NSDictionary *)initProps
@@ -192,9 +125,9 @@ - (void)setRootView:(UIView *)rootView toRootViewController:(UIViewController *)
   rootViewController.view = rootView;
 }
 
-- (BOOL)runtimeSchedulerEnabled
+- (void)customizeRootView:(RCTRootView *)rootView
 {
-  return YES;
+  // Override point for customization after application launch.
 }
 
 #pragma mark - UISceneDelegate
@@ -207,25 +140,6 @@ - (void)windowScene:(UIWindowScene *)windowScene
   [[NSNotificationCenter defaultCenter] postNotificationName:RCTWindowFrameDidChangeNotification object:self];
 }
 
-#pragma mark - RCTCxxBridgeDelegate
-
-- (std::unique_ptr<facebook::react::JSExecutorFactory>)jsExecutorFactoryForBridge:(RCTBridge *)bridge
-{
-  _runtimeScheduler = std::make_shared<facebook::react::RuntimeScheduler>(RCTRuntimeExecutorFromBridge(bridge));
-  if ([self newArchEnabled]) {
-    std::shared_ptr<facebook::react::CallInvoker> callInvoker =
-        std::make_shared<facebook::react::RuntimeSchedulerCallInvoker>(_runtimeScheduler);
-    RCTTurboModuleManager *turboModuleManager = [[RCTTurboModuleManager alloc] initWithBridge:bridge
-                                                                                     delegate:self
-                                                                                    jsInvoker:callInvoker];
-    _contextContainer->erase("RuntimeScheduler");
-    _contextContainer->insert("RuntimeScheduler", _runtimeScheduler);
-    return RCTAppSetupDefaultJsExecutorFactory(bridge, turboModuleManager, _runtimeScheduler);
-  } else {
-    return RCTAppSetupJsExecutorFactoryForOldArch(bridge, _runtimeScheduler);
-  }
-}
-
 #pragma mark - New Arch Enabled settings
 
 - (BOOL)newArchEnabled
@@ -252,11 +166,33 @@ - (BOOL)bridgelessEnabled
   return [self newArchEnabled];
 }
 
-#pragma mark - RCTComponentViewFactoryComponentProvider
+- (NSURL *)bundleURL
+{
+  [NSException raise:@"RCTAppDelegate::bundleURL not implemented"
+              format:@"Subclasses must implement a valid getBundleURL method"];
+  return nullptr;
+}
 
-- (NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents
+#pragma mark - Bridge and Bridge Adapter properties
+
+- (RCTBridge *)bridge
 {
-  return @{};
+  return self.rootViewFactory.bridge;
+}
+
+- (RCTSurfacePresenterBridgeAdapter *)bridgeAdapter
+{
+  return self.rootViewFactory.bridgeAdapter;
+}
+
+- (void)setBridge:(RCTBridge *)bridge
+{
+  self.rootViewFactory.bridge = bridge;
+}
+
+- (void)setBridgeAdapter:(RCTSurfacePresenterBridgeAdapter *)bridgeAdapter
+{
+  self.rootViewFactory.bridgeAdapter = bridgeAdapter;
 }
 
 #pragma mark - RCTTurboModuleManagerDelegate
@@ -288,43 +224,33 @@ - (Class)getModuleClassFromName:(const char *)name
   return RCTAppSetupDefaultModuleFromClass(moduleClass);
 }
 
-#pragma mark - New Arch Utilities
+#pragma mark - RCTComponentViewFactoryComponentProvider
 
-- (void)createReactHost
+- (NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents
 {
-  __weak __typeof(self) weakSelf = self;
-  _reactHost = [[RCTHost alloc] initWithBundleURL:[self bundleURL]
-                                     hostDelegate:nil
-                       turboModuleManagerDelegate:self
-                                 jsEngineProvider:^std::shared_ptr<facebook::react::JSRuntimeFactory>() {
-                                   return [weakSelf createJSRuntimeFactory];
-                                 }];
-  [_reactHost setBundleURLProvider:^NSURL *() {
-    return [weakSelf bundleURL];
-  }];
-  [_reactHost setContextContainerHandler:self];
-  [_reactHost start];
+  return @{};
 }
 
-- (std::shared_ptr<facebook::react::JSRuntimeFactory>)createJSRuntimeFactory
+- (RCTRootViewFactory *)createRCTRootViewFactory
 {
-#if USE_HERMES
-  return std::make_shared<facebook::react::RCTHermesInstance>(_reactNativeConfig, nullptr);
-#else
-  return std::make_shared<facebook::react::RCTJscInstance>();
-#endif
-}
+  RCTRootViewFactoryConfiguration *configuration =
+      [[RCTRootViewFactoryConfiguration alloc] initWithBundleURL:self.bundleURL
+                                                  newArchEnabled:self.fabricEnabled
+                                              turboModuleEnabled:self.turboModuleEnabled
+                                               bridgelessEnabled:self.bridgelessEnabled];
 
-- (void)didCreateContextContainer:(std::shared_ptr<facebook::react::ContextContainer>)contextContainer
-{
-  contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
-}
+  __weak __typeof(self) weakSelf = self;
+  configuration.createRootViewWithBridge = ^UIView *(RCTBridge *bridge, NSString *moduleName, NSDictionary *initProps)
+  {
+    return [weakSelf createRootViewWithBridge:bridge moduleName:moduleName initProps:initProps];
+  };
 
-- (NSURL *)bundleURL
-{
-  [NSException raise:@"RCTAppDelegate::bundleURL not implemented"
-              format:@"Subclasses must implement a valid getBundleURL method"];
-  return nullptr;
+  configuration.createBridgeWithDelegate = ^RCTBridge *(id<RCTBridgeDelegate> delegate, NSDictionary *launchOptions)
+  {
+    return [weakSelf createBridgeWithDelegate:delegate launchOptions:launchOptions];
+  };
+
+  return [[RCTRootViewFactory alloc] initWithConfiguration:configuration andTurboModuleManagerDelegate:self];
 }
 
 @end