Add more customization points in RCTAppDelegate

Libraries/AppDelegate/RCTAppDelegate.h

@@ -35,7 +35,12 @@
  * If you need to customize the default implementation, you can invoke `[super <method_name>]` and use the returned
  object.
  *
- * Overridable methods (New Architecture):
+ * Overridable methods
+ * Shared:
+ *   - (RCTBridge *)createBridgeWithDelegate:(id<RCTBridgeDelegate>)delegate launchOptions:(NSDictionary *)launchOptions;
+ *   - (UIView *)createRootViewWithBridge:(RCTBridge *)bridge moduleName:(NSString*)moduleName initProps:(NSDictionary *)initProps;
+ *   - (UIViewController *)createRootViewController;
+ * New Architecture:
  *   - (BOOL)concurrentRootEnabled
  *   - (NSDictionary *)prepareInitialProps
  *   - (Class)getModuleClassFromName:(const char *)name
@@ -53,6 +58,41 @@
 @property (nonatomic, strong) RCTBridge *bridge;
 @property (nonatomic, strong) NSString *moduleName;
 
+/**
+ * It creates a `RCTBridge` using a delegate and some launch options.
+ * By default, it is invoked passing `self` as a delegate.
+ * You can override this function to customize the logic that creates the RCTBridge
+ *
+ * @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.
+ */
+- (RCTBridge *)createBridgeWithDelegate:(id<RCTBridgeDelegate>)delegate launchOptions:(NSDictionary *)launchOptions;
+
+/**
+ * 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 `createBridgeWithDelegate:launchOptions` and
+ * the name in the `self.moduleName` variable.
+ * You can override this function to customize the logic that creates the Root View.
+ *
+ * @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.
+ */
+- (UIView *)createRootViewWithBridge:(RCTBridge *)bridge moduleName:(NSString*)moduleName initProps:(NSDictionary *)initProps;
+
+/**
+ * It creates the RootViewController.
+ * By default, it creates a new instance of a `UIViewController`.
+ * You can override it to provide your own initial ViewController.
+ *
+ * @return: an instance of `UIViewController`.
+ */
+- (UIViewController *)createRootViewController;
+
 @end
 
 #if RCT_NEW_ARCH_ENABLED

Libraries/AppDelegate/RCTAppDelegate.mm

@@ -32,7 +32,7 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
   RCTAppSetupPrepareApp(application);
 
   if (!self.bridge) {
-    self.bridge = [[RCTBridge alloc] initWithDelegate:self launchOptions:launchOptions];
+    self.bridge = [self createBridgeWithDelegate:self launchOptions:launchOptions];
   }
 #if RCT_NEW_ARCH_ENABLED
   _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
@@ -43,7 +43,7 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
 #endif
 
   NSDictionary *initProps = [self prepareInitialProps];
-  UIView *rootView = RCTAppSetupDefaultRootView(self.bridge, self.moduleName, initProps);
+  UIView *rootView = [self createRootViewWithBridge:self.bridge moduleName:self.moduleName initProps:initProps];
 
   if (@available(iOS 13.0, *)) {
     rootView.backgroundColor = [UIColor systemBackgroundColor];
@@ -52,7 +52,7 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
   }
 
   self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
-  UIViewController *rootViewController = [UIViewController new];
+  UIViewController *rootViewController = [self createRootViewController];
   rootViewController.view = rootView;
   self.window.rootViewController = rootViewController;
   [self.window makeKeyAndVisible];
@@ -88,6 +88,21 @@ - (NSDictionary *)prepareInitialProps
   return 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
+{
+  return RCTAppSetupDefaultRootView(bridge, moduleName, initProps);
+}
+
+- (UIViewController *)createRootViewController
+{
+  return [UIViewController new];
+}
+
 #if RCT_NEW_ARCH_ENABLED
 #pragma mark - RCTCxxBridgeDelegate