Follow-up with Review Feedback on RCTAppDelegate from #43526

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

@@ -265,19 +265,42 @@ - (RCTRootViewFactory *)createRCTRootViewFactory
     return [weakSelf sourceURLForBridge:bridge];
   };
 
-  configuration.extraModulesForBridge = ^NSArray<id<RCTBridgeModule>> *_Nonnull(RCTBridge *_Nonnull bridge)
-  {
-    return [weakSelf extraModulesForBridge:bridge];
-  };
+  if ([self respondsToSelector:@selector(extraModulesForBridge:)]) {
+    configuration.extraModulesForBridge = ^NSArray<id<RCTBridgeModule>> *_Nonnull(RCTBridge *_Nonnull bridge)
+    {
+      return [weakSelf extraModulesForBridge:bridge];
+    };
+  }
 
-  configuration.extraLazyModuleClassesForBridge = ^NSDictionary<NSString *, Class> *_Nonnull(RCTBridge *_Nonnull bridge)
-  {
-    return [weakSelf extraLazyModuleClassesForBridge:bridge];
-  };
+  if ([self respondsToSelector:@selector(extraLazyModuleClassesForBridge:)]) {
+    configuration.extraLazyModuleClassesForBridge =
+        ^NSDictionary<NSString *, Class> *_Nonnull(RCTBridge *_Nonnull bridge)
+    {
+      return [weakSelf extraLazyModuleClassesForBridge:bridge];
+    };
+  }
 
-  configuration.bridgeDidNotFindModule = ^BOOL(RCTBridge *_Nonnull bridge, NSString *_Nonnull moduleName) {
-    return [weakSelf bridge:bridge didNotFindModule:moduleName];
-  };
+  if ([self respondsToSelector:@selector(bridge:didNotFindModule:)]) {
+    configuration.bridgeDidNotFindModule = ^BOOL(RCTBridge *_Nonnull bridge, NSString *_Nonnull moduleName) {
+      return [weakSelf bridge:bridge didNotFindModule:moduleName];
+    };
+  }
+
+  if ([self respondsToSelector:@selector(loadSourceForBridge:withBlock:)]) {
+    configuration.loadSourceForBridgeBlock =
+        ^void(RCTBridge *_Nonnull bridge, RCTSourceLoadBlock _Nonnull loadCallback) {
+          [weakSelf loadSourceForBridge:bridge withBlock:loadCallback];
+        };
+  }
+
+  if ([self respondsToSelector:@selector(loadSourceForBridge:onProgress:onComplete:)]) {
+    configuration.loadSourceForBridgeProgressBlock =
+        ^(RCTBridge *_Nonnull bridge,
+          RCTSourceLoadProgressBlock _Nonnull onProgress,
+          RCTSourceLoadBlock _Nonnull loadCallback) {
+          [weakSelf loadSourceForBridge:bridge onProgress:onProgress onComplete:loadCallback];
+        };
+  }
 
   return [[RCTRootViewFactory alloc] initWithConfiguration:configuration andTurboModuleManagerDelegate:self];
 }

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

@@ -27,6 +27,11 @@ typedef NSURL *_Nullable (^RCTSourceURLForBridgeBlock)(RCTBridge *bridge);
 typedef NSArray<id<RCTBridgeModule>> *_Nonnull (^RCTExtraModulesForBridgeBlock)(RCTBridge *bridge);
 typedef NSDictionary<NSString *, Class> *_Nonnull (^RCTExtraLazyModuleClassesForBridge)(RCTBridge *bridge);
 typedef BOOL (^RCTBridgeDidNotFindModuleBlock)(RCTBridge *bridge, NSString *moduleName);
+typedef void (^RCTLoadSourceForBridgeBlock)(RCTBridge *bridge, RCTSourceLoadBlock loadCallback);
+typedef void (^RCTLoadSourceForBridgeProgressBlock)(
+    RCTBridge *bridge,
+    RCTSourceLoadProgressBlock onProgress,
+    RCTSourceLoadBlock loadCallback);
 
 #pragma mark - RCTRootViewFactory Configuration
 @interface RCTRootViewFactoryConfiguration : NSObject
@@ -84,7 +89,6 @@ typedef BOOL (^RCTBridgeDidNotFindModuleBlock)(RCTBridge *bridge, NSString *modu
  * @returns: a newly created instance of RCTBridge.
  */
 @property (nonatomic, nullable) RCTCreateBridgeWithDelegateBlock createBridgeWithDelegate;
-
 /**
  * Block that returns 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`.
@@ -123,6 +127,19 @@ typedef BOOL (^RCTBridgeDidNotFindModuleBlock)(RCTBridge *bridge, NSString *modu
  */
 @property (nonatomic, nullable) RCTBridgeDidNotFindModuleBlock bridgeDidNotFindModule;
 
+/**
+ * The bridge will automatically attempt to load the JS source code from the
+ * location specified by the `sourceURLForBridge:` method, however, if you want
+ * to handle loading the JS yourself, you can do so by implementing this method.
+ */
+@property (nonatomic, nullable) RCTLoadSourceForBridgeProgressBlock loadSourceForBridgeProgressBlock;
+
+/**
+ * Similar to loadSourceForBridge:onProgress:onComplete: but without progress
+ * reporting.
+ */
+@property (nonatomic, nullable) RCTLoadSourceForBridgeBlock loadSourceForBridgeBlock;
+
 @end
 
 #pragma mark - RCTRootViewFactory

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

@@ -273,6 +273,22 @@ - (BOOL)bridge:(RCTBridge *)bridge didNotFindModule:(NSString *)moduleName
   return NO;
 }
 
+- (void)loadSourceForBridge:(RCTBridge *)bridge withBlock:(RCTSourceLoadBlock)loadCallback
+{
+  if (_configuration.loadSourceForBridgeBlock != nil) {
+    _configuration.loadSourceForBridgeBlock(bridge, loadCallback);
+  }
+}
+
+- (void)loadSourceForBridge:(RCTBridge *)bridge
+                 onProgress:(RCTSourceLoadProgressBlock)onProgress
+                 onComplete:(RCTSourceLoadBlock)loadCallback
+{
+  if (_configuration.loadSourceForBridgeProgressBlock != nil) {
+    _configuration.loadSourceForBridgeProgressBlock(bridge, onProgress, loadCallback);
+  }
+}
+
 - (NSURL *)bundleURL
 {
   return self->_configuration.bundleURL;