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.

### Brownfield use case

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

## Changelog:

[INTERNAL] [ADDED] - Implement RCTRootViewFactory

Pull Request resolved: https://github.com/facebook/react-native/pull/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

@@ -8,6 +8,7 @@
 #import <React/RCTBridgeDelegate.h>
 #import <React/RCTConvert.h>
 #import <UIKit/UIKit.h>
+#import "RCTRootViewFactory.h"
 
 @class RCTBridge;
 @protocol RCTBridgeDelegate;
@@ -58,9 +59,12 @@ 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.
@@ -127,18 +131,11 @@ 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;
-
 /**
  * The default `RCTColorSpace` for the app. It defaults to `RCTColorSpaceSRGB`.
  */
 @property (nonatomic, readonly) RCTColorSpace defaultColorSpace;
 
-@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

@@ -43,83 +43,29 @@
 #import <react/renderer/runtimescheduler/RuntimeSchedulerCallInvoker.h>
 #import <react/runtime/JSRuntimeFactory.h>
 
-@interface RCTAppDelegate () <RCTComponentViewFactoryComponentProvider, RCTContextContainerHandling> {
-  std::shared_ptr<const facebook::react::ReactNativeConfig> _reactNativeConfig;
-  facebook::react::ContextContainer::Shared _contextContainer;
-}
+@interface RCTAppDelegate () <RCTComponentViewFactoryComponentProvider>
 @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]);
   [RCTColorSpaceUtils applyDefaultColorSpace:self.defaultColorSpace];
-  BOOL enableTM = self.turboModuleEnabled;
-  BOOL fabricEnabled = self.fabricEnabled;
-  BOOL enableBridgeless = self.bridgelessEnabled;
+  RCTAppSetupPrepareApp(application, self.turboModuleEnabled);
 
-  NSDictionary *initProps = updateInitialProps([self prepareInitialProps], fabricEnabled);
+  self.rootViewFactory = [self createRCTRootViewFactory];
 
-  RCTAppSetupPrepareApp(application, enableTM);
+  UIView *rootView = [self.rootViewFactory viewWithModuleName:self.moduleName
+                                            initialProperties:self.initialProps
+                                                launchOptions:launchOptions];
 
-  UIView *rootView;
-  if (enableBridgeless) {
-    // Enable native view config interop only if both bridgeless mode and Fabric is enabled.
-    RCTSetUseNativeViewConfigsInBridgelessMode(fabricEnabled);
-
-    // 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];
@@ -142,21 +88,11 @@ static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabri
   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
@@ -194,9 +130,9 @@ static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabri
   rootViewController.view = rootView;
 }
 
-- (BOOL)runtimeSchedulerEnabled
+- (void)customizeRootView:(RCTRootView *)rootView
 {
-  return YES;
+  // Override point for customization after application launch.
 }
 
 #pragma mark - UISceneDelegate
@@ -209,25 +145,6 @@ static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabri
   [[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);
-  }
-}
-
 - (RCTColorSpace)defaultColorSpace
 {
   return RCTColorSpaceSRGB;
@@ -259,11 +176,33 @@ static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabri
   return [self newArchEnabled];
 }
 
-#pragma mark - RCTComponentViewFactoryComponentProvider
-
-- (NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents
+- (NSURL *)bundleURL
 {
-  return @{};
+  [NSException raise:@"RCTAppDelegate::bundleURL not implemented"
+              format:@"Subclasses must implement a valid getBundleURL method"];
+  return nullptr;
+}
+
+#pragma mark - Bridge and Bridge Adapter properties
+
+- (RCTBridge *)bridge
+{
+  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
@@ -299,43 +238,33 @@ static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabri
   return RCTAppSetupDefaultModuleFromClass(moduleClass);
 }
 
-#pragma mark - New Arch Utilities
+#pragma mark - RCTComponentViewFactoryComponentProvider
 
-- (void)createReactHost
+- (NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents
 {
+  return @{};
+}
+
+- (RCTRootViewFactory *)createRCTRootViewFactory
+{
+  RCTRootViewFactoryConfiguration *configuration =
+      [[RCTRootViewFactoryConfiguration alloc] initWithBundleURL:self.bundleURL
+                                                  newArchEnabled:self.fabricEnabled
+                                              turboModuleEnabled:self.turboModuleEnabled
+                                               bridgelessEnabled:self.bridgelessEnabled];
+
   __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];
-}
+  configuration.createRootViewWithBridge = ^UIView *(RCTBridge *bridge, NSString *moduleName, NSDictionary *initProps)
+  {
+    return [weakSelf createRootViewWithBridge:bridge moduleName:moduleName initProps:initProps];
+  };
 
-- (std::shared_ptr<facebook::react::JSRuntimeFactory>)createJSRuntimeFactory
-{
-#if USE_HERMES
-  return std::make_shared<facebook::react::RCTHermesInstance>(_reactNativeConfig, nullptr);
-#else
-  return std::make_shared<facebook::react::RCTJscInstance>();
-#endif
-}
+  configuration.createBridgeWithDelegate = ^RCTBridge *(id<RCTBridgeDelegate> delegate, NSDictionary *launchOptions)
+  {
+    return [weakSelf createBridgeWithDelegate:delegate launchOptions:launchOptions];
+  };
 
-- (void)didCreateContextContainer:(std::shared_ptr<facebook::react::ContextContainer>)contextContainer
-{
-  contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
-}
-
-- (NSURL *)bundleURL
-{
-  [NSException raise:@"RCTAppDelegate::bundleURL not implemented"
-              format:@"Subclasses must implement a valid getBundleURL method"];
-  return nullptr;
+  return [[RCTRootViewFactory alloc] initWithConfiguration:configuration andTurboModuleManagerDelegate:self];
 }
 
 @end

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

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <React/RCTBridge.h>
+#import <React/RCTRootView.h>
+#import <React/RCTUtils.h>
+
+@protocol RCTCxxBridgeDelegate;
+@protocol RCTComponentViewFactoryComponentProvider;
+@protocol RCTTurboModuleManagerDelegate;
+@class RCTBridge;
+@class RCTRootView;
+@class RCTSurfacePresenterBridgeAdapter;
+
+NS_ASSUME_NONNULL_BEGIN
+
+#pragma mark - Blocks' definitions
+typedef UIView *_Nonnull (
+    ^RCTCreateRootViewWithBridgeBlock)(RCTBridge *bridge, NSString *moduleName, NSDictionary *initProps);
+typedef RCTBridge *_Nonnull (
+    ^RCTCreateBridgeWithDelegateBlock)(id<RCTBridgeDelegate> delegate, NSDictionary *launchOptions);
+
+#pragma mark - RCTRootViewFactory Configuration
+@interface RCTRootViewFactoryConfiguration : NSObject
+
+/// This property controls whether the App will use the Fabric renderer of the New Architecture or not.
+@property (nonatomic, assign, readonly) BOOL fabricEnabled;
+
+/// This property controls whether React Native's new initialization layer is enabled.
+@property (nonatomic, assign, readonly) BOOL bridgelessEnabled;
+
+/// This method controls whether the `turboModules` feature of the New Architecture is turned on or off
+@property (nonatomic, assign, readonly) BOOL turboModuleEnabled;
+
+/// Return the bundle URL for the main bundle.
+@property (nonatomic) NSURL *bundleURL;
+
+/**
+ * Use this method to initialize a new instance of `RCTRootViewFactoryConfiguration` by passing a `bundleURL`
+ *
+ * Which is the location of the JavaScript source file. When running from the packager
+ * this should be an absolute URL, e.g. `http://localhost:8081/index.ios.bundle`.
+ * When running from a locally bundled JS file, this should be a `file://` url
+ * pointing to a path inside the app resources, e.g. `file://.../main.jsbundle`.
+ *
+ */
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                   newArchEnabled:(BOOL)newArchEnabled
+               turboModuleEnabled:(BOOL)turboModuleEnabled
+                bridgelessEnabled:(BOOL)bridgelessEnabled;
+
+/**
+ * Block that allows to override logic of creating root view instance.
+ * It creates a `UIView` starting from a bridge, a module name and a set of initial properties.
+ * By default, it is invoked using the bridge created by `RCTCreateBridgeWithDelegateBlock` (or the default
+ * implementation) and the `moduleName` variable comes from `viewWithModuleName:initialProperties:launchOptions` of
+ * `RCTRootViewFactory`.
+ *
+ * @parameter: bridge - an instance of the `RCTBridge` object.
+ * @parameter: moduleName - the name of the app, used by Metro to resolve the module.
+ * @parameter: initProps - a set of initial properties.
+ *
+ * @returns: a UIView properly configured with a bridge for React Native.
+ */
+@property (nonatomic, nullable) RCTCreateRootViewWithBridgeBlock createRootViewWithBridge;
+
+/**
+ * Block that allows to override default behavior of creating bridge.
+ * It should return `RCTBridge` using a delegate and some launch options.
+ *
+ * By default, it is invoked passing `self` as a delegate.
+ *
+ * @parameter: delegate - an object that implements the `RCTBridgeDelegate` protocol.
+ * @parameter: launchOptions - a dictionary with a set of options.
+ *
+ * @returns: a newly created instance of RCTBridge.
+ */
+@property (nonatomic, nullable) RCTCreateBridgeWithDelegateBlock createBridgeWithDelegate;
+
+@end
+
+#pragma mark - RCTRootViewFactory
+/**
+ * The RCTRootViewFactory is an utility class that encapsulates the logic of creating a new RCTRootView based on the
+ * current state of the environment. It allows you to initialize your app root view for old architecture, new
+ * architecture and bridgless mode.
+ *
+ * This class is used to initalize rootView in RCTAppDelegate, but you can also use it separately.
+ *
+ * Create a new instance of this class (make sure to retain it) and call the
+ * `viewWithModuleName:initialProperties:launchOptions` method to create new RCTRootView.
+ */
+@interface RCTRootViewFactory : NSObject
+
+@property (nonatomic, strong, nullable) RCTBridge *bridge;
+@property (nonatomic, strong, nullable) RCTSurfacePresenterBridgeAdapter *bridgeAdapter;
+
+- (instancetype)initWithConfiguration:(RCTRootViewFactoryConfiguration *)configuration
+        andTurboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)turboModuleManagerDelegate;
+
+/**
+ * This method can be used to create new RCTRootViews on demand.
+ *
+ * @parameter: moduleName  - the name of the app, used by Metro to resolve the module.
+ * @parameter: initialProperties  -  a set of initial properties.
+ * @parameter: moduleName  - a dictionary with a set of options.
+ */
+- (UIView *_Nonnull)viewWithModuleName:(NSString *)moduleName
+                     initialProperties:(NSDictionary *__nullable)initialProperties
+                         launchOptions:(NSDictionary *__nullable)launchOptions;
+
+- (UIView *_Nonnull)viewWithModuleName:(NSString *)moduleName
+                     initialProperties:(NSDictionary *__nullable)initialProperties;
+
+- (UIView *_Nonnull)viewWithModuleName:(NSString *)moduleName;
+
+@end
+
+NS_ASSUME_NONNULL_END

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

@@ -0,0 +1,253 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTRootViewFactory.h"
+#import <React/RCTCxxBridgeDelegate.h>
+#import <React/RCTLog.h>
+#import <React/RCTRootView.h>
+#import <React/RCTSurfacePresenterBridgeAdapter.h>
+#import <React/RCTUtils.h>
+#import <react/renderer/runtimescheduler/RuntimeScheduler.h>
+#import "RCTAppDelegate.h"
+#import "RCTAppSetupUtils.h"
+
+#if RN_DISABLE_OSS_PLUGIN_HEADER
+#import <RCTTurboModulePlugin/RCTTurboModulePlugin.h>
+#else
+#import <React/CoreModulesPlugins.h>
+#endif
+#import <React/RCTBundleURLProvider.h>
+#import <React/RCTComponentViewFactory.h>
+#import <React/RCTComponentViewProtocol.h>
+#import <React/RCTFabricSurface.h>
+#import <React/RCTSurfaceHostingProxyRootView.h>
+#import <React/RCTSurfacePresenter.h>
+#import <ReactCommon/RCTContextContainerHandling.h>
+#if USE_HERMES
+#import <ReactCommon/RCTHermesInstance.h>
+#else
+#import <ReactCommon/RCTJscInstance.h>
+#endif
+#import <ReactCommon/RCTHost+Internal.h>
+#import <ReactCommon/RCTHost.h>
+#import <ReactCommon/RCTTurboModuleManager.h>
+#import <react/config/ReactNativeConfig.h>
+#import <react/renderer/runtimescheduler/RuntimeScheduler.h>
+#import <react/renderer/runtimescheduler/RuntimeSchedulerCallInvoker.h>
+#import <react/runtime/JSRuntimeFactory.h>
+
+static NSString *const kRNConcurrentRoot = @"concurrentRoot";
+
+static NSDictionary *updateInitialProps(NSDictionary *initialProps, BOOL isFabricEnabled)
+{
+  NSMutableDictionary *mutableProps = initialProps != NULL ? [initialProps mutableCopy] : [NSMutableDictionary new];
+  // Hardcoding the Concurrent Root as it it not recommended to
+  // have the concurrentRoot turned off when Fabric is enabled.
+  mutableProps[kRNConcurrentRoot] = @(isFabricEnabled);
+  return mutableProps;
+}
+
+@implementation RCTRootViewFactoryConfiguration
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                   newArchEnabled:(BOOL)newArchEnabled
+               turboModuleEnabled:(BOOL)turboModuleEnabled
+                bridgelessEnabled:(BOOL)bridgelessEnabled
+{
+  if (self = [super init]) {
+    _bundleURL = bundleURL;
+    _fabricEnabled = newArchEnabled;
+    _turboModuleEnabled = turboModuleEnabled;
+    _bridgelessEnabled = bridgelessEnabled;
+  }
+  return self;
+}
+
+@end
+
+@interface RCTRootViewFactory () <RCTContextContainerHandling> {
+  std::shared_ptr<const facebook::react::ReactNativeConfig> _reactNativeConfig;
+  facebook::react::ContextContainer::Shared _contextContainer;
+}
+@end
+
+@interface RCTRootViewFactory () <RCTCxxBridgeDelegate> {
+  std::shared_ptr<facebook::react::RuntimeScheduler> _runtimeScheduler;
+}
+@end
+
+@implementation RCTRootViewFactory {
+  RCTHost *_reactHost;
+  RCTRootViewFactoryConfiguration *_configuration;
+  __weak id<RCTTurboModuleManagerDelegate> _turboModuleManagerDelegate;
+}
+
+- (instancetype)initWithConfiguration:(RCTRootViewFactoryConfiguration *)configuration
+        andTurboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)turboModuleManagerDelegate
+{
+  if (self = [super init]) {
+    _configuration = configuration;
+    _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
+    _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
+    _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
+    _turboModuleManagerDelegate = turboModuleManagerDelegate;
+  }
+  return self;
+}
+
+- (UIView *)viewWithModuleName:(NSString *)moduleName initialProperties:(NSDictionary *)initialProperties
+{
+  return [self viewWithModuleName:moduleName initialProperties:initialProperties launchOptions:nil];
+}
+
+- (UIView *)viewWithModuleName:(NSString *)moduleName
+{
+  return [self viewWithModuleName:moduleName initialProperties:nil launchOptions:nil];
+}
+
+- (UIView *)viewWithModuleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+                 launchOptions:(NSDictionary *)launchOptions
+{
+  NSDictionary *initProps = updateInitialProps(initialProperties, self->_configuration.fabricEnabled);
+
+  if (self->_configuration.bridgelessEnabled) {
+    // Enable native view config interop only if both bridgeless mode and Fabric is enabled.
+    RCTSetUseNativeViewConfigsInBridgelessMode(self->_configuration.fabricEnabled);
+
+    // Enable TurboModule interop by default in Bridgeless mode
+    RCTEnableTurboModuleInterop(YES);
+    RCTEnableTurboModuleInteropBridgeProxy(YES);
+
+    [self createReactHostIfNeeded];
+
+    RCTFabricSurface *surface = [_reactHost createSurfaceWithModuleName:moduleName initialProperties:initProps];
+
+    RCTSurfaceHostingProxyRootView *surfaceHostingProxyRootView = [[RCTSurfaceHostingProxyRootView alloc]
+        initWithSurface:surface
+        sizeMeasureMode:RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightExact];
+
+    return surfaceHostingProxyRootView;
+  }
+
+  [self createBridgeIfNeeded:launchOptions];
+  [self createBridgeAdapterIfNeeded];
+
+  if (self->_configuration.createRootViewWithBridge != nil) {
+    return self->_configuration.createRootViewWithBridge(self.bridge, moduleName, initProps);
+  }
+
+  return [self createRootViewWithBridge:self.bridge moduleName:moduleName initProps:initProps];
+}
+
+- (RCTBridge *)createBridgeWithDelegate:(id<RCTBridgeDelegate>)delegate launchOptions:(NSDictionary *)launchOptions
+{
+  return [[RCTBridge alloc] initWithDelegate:delegate launchOptions:launchOptions];
+}
+
+- (UIView *)createRootViewWithBridge:(RCTBridge *)bridge
+                          moduleName:(NSString *)moduleName
+                           initProps:(NSDictionary *)initProps
+{
+  BOOL enableFabric = self->_configuration.fabricEnabled;
+  UIView *rootView = RCTAppSetupDefaultRootView(bridge, moduleName, initProps, enableFabric);
+
+  rootView.backgroundColor = [UIColor systemBackgroundColor];
+
+  return rootView;
+}
+
+#pragma mark - RCTCxxBridgeDelegate
+- (std::unique_ptr<facebook::react::JSExecutorFactory>)jsExecutorFactoryForBridge:(RCTBridge *)bridge
+{
+  _runtimeScheduler = std::make_shared<facebook::react::RuntimeScheduler>(RCTRuntimeExecutorFromBridge(bridge));
+  if (RCTIsNewArchEnabled()) {
+    std::shared_ptr<facebook::react::CallInvoker> callInvoker =
+        std::make_shared<facebook::react::RuntimeSchedulerCallInvoker>(_runtimeScheduler);
+    RCTTurboModuleManager *turboModuleManager =
+        [[RCTTurboModuleManager alloc] initWithBridge:bridge
+                                             delegate:_turboModuleManagerDelegate
+                                            jsInvoker:callInvoker];
+    _contextContainer->erase("RuntimeScheduler");
+    _contextContainer->insert("RuntimeScheduler", _runtimeScheduler);
+    return RCTAppSetupDefaultJsExecutorFactory(bridge, turboModuleManager, _runtimeScheduler);
+  } else {
+    return RCTAppSetupJsExecutorFactoryForOldArch(bridge, _runtimeScheduler);
+  }
+}
+
+- (void)createBridgeIfNeeded:(NSDictionary *)launchOptions
+{
+  if (self.bridge != nil) {
+    return;
+  }
+
+  if (self->_configuration.createBridgeWithDelegate != nil) {
+    self.bridge = self->_configuration.createBridgeWithDelegate(self, launchOptions);
+  } else {
+    self.bridge = [self createBridgeWithDelegate:self launchOptions:launchOptions];
+  }
+}
+
+- (void)createBridgeAdapterIfNeeded
+{
+  if (!self->_configuration.fabricEnabled || self.bridgeAdapter) {
+    return;
+  }
+
+  self.bridgeAdapter = [[RCTSurfacePresenterBridgeAdapter alloc] initWithBridge:self.bridge
+                                                               contextContainer:_contextContainer];
+  self.bridge.surfacePresenter = self.bridgeAdapter.surfacePresenter;
+}
+
+#pragma mark - New Arch Utilities
+
+- (void)createReactHostIfNeeded
+{
+  if (_reactHost) {
+    return;
+  }
+
+  __weak __typeof(self) weakSelf = self;
+  _reactHost = [[RCTHost alloc] initWithBundleURL:[self bundleURL]
+                                     hostDelegate:nil
+                       turboModuleManagerDelegate:_turboModuleManagerDelegate
+                                 jsEngineProvider:^std::shared_ptr<facebook::react::JSRuntimeFactory>() {
+                                   return [weakSelf createJSRuntimeFactory];
+                                 }];
+  [_reactHost setBundleURLProvider:^NSURL *() {
+    return [weakSelf bundleURL];
+  }];
+  [_reactHost setContextContainerHandler:self];
+  [_reactHost start];
+}
+
+- (std::shared_ptr<facebook::react::JSRuntimeFactory>)createJSRuntimeFactory
+{
+#if USE_HERMES
+  return std::make_shared<facebook::react::RCTHermesInstance>(_reactNativeConfig, nullptr);
+#else
+  return std::make_shared<facebook::react::RCTJscInstance>();
+#endif
+}
+
+- (void)didCreateContextContainer:(std::shared_ptr<facebook::react::ContextContainer>)contextContainer
+{
+  contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
+}
+
+- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge
+{
+  return [self bundleURL];
+}
+
+- (NSURL *)bundleURL
+{
+  return self->_configuration.bundleURL;
+}
+
+@end

packages/rn-tester/RNTester/NativeExampleViews/FlexibleSizeExampleView.mm

@@ -46,9 +46,8 @@ RCT_EXPORT_MODULE();
 
     AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
 
-    _resizableRootView = [[RCTRootView alloc] initWithBridge:appDelegate.bridge
-                                                  moduleName:@"RootViewSizeFlexibilityExampleApp"
-                                           initialProperties:@{}];
+    _resizableRootView =
+        (RCTRootView *)[appDelegate.rootViewFactory viewWithModuleName:@"RootViewSizeFlexibilityExampleApp"];
 
     [_resizableRootView setSizeFlexibility:RCTRootViewSizeFlexibilityHeight];
 

packages/rn-tester/RNTester/NativeExampleViews/UpdatePropertiesExampleView.mm

@@ -41,9 +41,8 @@ RCT_EXPORT_MODULE();
 
     AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
 
-    _rootView = [[RCTRootView alloc] initWithBridge:appDelegate.bridge
-                                         moduleName:@"SetPropertiesExampleApp"
-                                  initialProperties:@{@"color" : @"beige"}];
+    _rootView = (RCTRootView *)[appDelegate.rootViewFactory viewWithModuleName:@"SetPropertiesExampleApp"
+                                                             initialProperties:@{@"color" : @"beige"}];
 
     _button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
     [_button setTitle:@"Native Button" forState:UIControlStateNormal];