fix(ios): enable use of multiple RCTAppDependencyProvider instances (#49889)

Summary:
instantiating multiple `RCTAppDependencyProvider` instances creates problems with their internal state, because the internal fields such as [`_thirdPartyFabricComponents` are populated once](https://github.com/facebook/react-native/blob/f5feb73022f9340583ebcf576eaedd3ca5677e1a/packages/react-native/scripts/codegen/templates/RCTAppDependencyProviderMM.template#L60) for the entire app (see [`dispatch_once`](https://developer.apple.com/documentation/dispatch/1447169-dispatch_once)).

That means when you create 2 instances, and call `thirdPartyFabricComponents` on them, the first instance will respond with a dictionary and the second with `nil`. This is unexpected.

## Changelog:

[IOS] [FIXED] - enable use of multiple `RCTAppDependencyProvider` instances

Pull Request resolved: #49889

Test Plan:
`rnTester` - the templates are used by codegen. Running `pod install`, the files were generated correctly from the `.template` files.

I was able to verify that accessing `thirdPartyFabricComponents` on multiple instances of `RCTAppDependencyProvider` returns valid result.

<details>
<summary>screenshot</summary>

<img width="789" alt="Screenshot 2025-03-07 at 15 11 22" src="https://github.com/user-attachments/assets/9270ba90-ae7f-491a-a53a-f7e1f4606438" />

</details>

Reviewed By: javache

Differential Revision: D70892779

Pulled By: cipolleschi

fbshipit-source-id: 27c7c8fd9982b6427daec02e0de59b08ad20bfad

Author: vonovak

packages/react-native/scripts/codegen/generate-artifacts-executor.js

@@ -613,7 +613,7 @@ function generateCustomURLHandlers(libraries, outputDir) {
     )
     .filter(Boolean)
     .map(className => `@"${className}"`)
-    .join(',\n\t\t');
+    .join(',\n\t\t\t');
 
   const customImageDataDecoderClasses = libraries
     .flatMap(
@@ -622,7 +622,7 @@ function generateCustomURLHandlers(libraries, outputDir) {
     )
     .filter(Boolean)
     .map(className => `@"${className}"`)
-    .join(',\n\t\t');
+    .join(',\n\t\t\t');
 
   const customURLHandlerClasses = libraries
     .flatMap(
@@ -631,7 +631,7 @@ function generateCustomURLHandlers(libraries, outputDir) {
     )
     .filter(Boolean)
     .map(className => `@"${className}"`)
-    .join(',\n\t\t');
+    .join(',\n\t\t\t');
 
   const template = fs.readFileSync(MODULES_PROTOCOLS_MM_TEMPLATE_PATH, 'utf8');
   const finalMMFile = template
@@ -736,7 +736,7 @@ function generateRCTModuleProviders(
     .flatMap(library => {
       const modules = modulesInLibraries[library];
       return modules.map(({moduleName, className}) => {
-        return `\t\t@"${moduleName}": @"${className}", // ${library}`;
+        return `\t\t\t@"${moduleName}": @"${className}", // ${library}`;
       });
     })
     .join('\n');
@@ -805,7 +805,7 @@ function generateRCTThirdPartyComponents(libraries, outputDir) {
     .flatMap(library => {
       const components = componentsInLibraries[library];
       return components.map(({componentName, className}) => {
-        return `\t\t@"${componentName}": NSClassFromString(@"${className}"), // ${library}`;
+        return `\t\t\t@"${componentName}": NSClassFromString(@"${className}"), // ${library}`;
       });
     })
     .join('\n');

packages/react-native/scripts/codegen/templates/RCTAppDependencyProviderMM.template

@@ -10,56 +10,26 @@
 #import <ReactCodegen/RCTThirdPartyComponentsProvider.h>
 #import <ReactCodegen/RCTModuleProviders.h>
 
-@implementation RCTAppDependencyProvider {
-  NSArray<NSString *> * _URLRequestHandlerClassNames;
-  NSArray<NSString *> * _imageDataDecoderClassNames;
-  NSArray<NSString *> * _imageURLLoaderClassNames;
-  NSDictionary<NSString *,Class<RCTComponentViewProtocol>> * _thirdPartyFabricComponents;
-  NSDictionary<NSString *, id<RCTModuleProvider>> * _moduleProviders;
-}
+@implementation RCTAppDependencyProvider
 
 - (nonnull NSArray<NSString *> *)URLRequestHandlerClassNames {
-  static dispatch_once_t requestUrlToken;
-  dispatch_once(&requestUrlToken, ^{
-    self->_URLRequestHandlerClassNames = RCTModulesConformingToProtocolsProvider.URLRequestHandlerClassNames;
-  });
-
-  return _URLRequestHandlerClassNames;
+  return RCTModulesConformingToProtocolsProvider.URLRequestHandlerClassNames;
 }
 
 - (nonnull NSArray<NSString *> *)imageDataDecoderClassNames {
-  static dispatch_once_t dataDecoderToken;
-  dispatch_once(&dataDecoderToken, ^{
-    _imageDataDecoderClassNames = RCTModulesConformingToProtocolsProvider.imageDataDecoderClassNames;
-  });
-
-  return _imageDataDecoderClassNames;
+  return RCTModulesConformingToProtocolsProvider.imageDataDecoderClassNames;
 }
 
 - (nonnull NSArray<NSString *> *)imageURLLoaderClassNames {
-  static dispatch_once_t urlLoaderToken;
-  dispatch_once(&urlLoaderToken, ^{
-    _imageURLLoaderClassNames = RCTModulesConformingToProtocolsProvider.imageURLLoaderClassNames;
-  });
-
-  return _imageURLLoaderClassNames;
+  return RCTModulesConformingToProtocolsProvider.imageURLLoaderClassNames;
 }
 
 - (nonnull NSDictionary<NSString *,Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents {
-  static dispatch_once_t nativeComponentsToken;
-  dispatch_once(&nativeComponentsToken, ^{
-    _thirdPartyFabricComponents = RCTThirdPartyComponentsProvider.thirdPartyFabricComponents;
-  });
-
-  return _thirdPartyFabricComponents;
+  return RCTThirdPartyComponentsProvider.thirdPartyFabricComponents;
 }
 
 - (nonnull NSDictionary<NSString *, id<RCTModuleProvider>> *)moduleProviders {
-  static dispatch_once_t modulesToken;
-  dispatch_once(&modulesToken, ^{
-    _moduleProviders = RCTModuleProviders.moduleProviders;
-  });
-  return _moduleProviders;
+  return RCTModuleProviders.moduleProviders;
 }
 
 @end

packages/react-native/scripts/codegen/templates/RCTModuleProvidersMM.template

@@ -15,30 +15,37 @@
 
 + (NSDictionary<NSString *, id<RCTModuleProvider>> *)moduleProviders
 {
-  NSDictionary<NSString *, NSString *> * moduleMapping = @{
-    {moduleMapping}
-  };
-
-  NSMutableDictionary *dict = [NSMutableDictionary new];
-
-  for (NSString *key in moduleMapping) {
-    NSString * moduleProviderName = moduleMapping[key];
-    Class klass = NSClassFromString(moduleProviderName);
-    if (!klass) {
-      RCTLogError(@"Module provider %@ cannot be found in the runtime", moduleProviderName);
-      continue;
+  static NSDictionary<NSString *, id<RCTModuleProvider>> *providers = nil;
+  static dispatch_once_t onceToken;
+
+  dispatch_once(&onceToken, ^{
+    NSDictionary<NSString *, NSString *> * moduleMapping = @{
+      {moduleMapping}
+    };
+
+    NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithCapacity:moduleMapping.count];
+
+    for (NSString *key in moduleMapping) {
+      NSString * moduleProviderName = moduleMapping[key];
+      Class klass = NSClassFromString(moduleProviderName);
+      if (!klass) {
+        RCTLogError(@"Module provider %@ cannot be found in the runtime", moduleProviderName);
+        continue;
+      }
+
+      id instance = [klass new];
+      if (![instance respondsToSelector:@selector(getTurboModule:)]) {
+        RCTLogError(@"Module provider %@ does not conform to RCTModuleProvider", moduleProviderName);
+        continue;
+      }
+
+      [dict setObject:instance forKey:key];
     }
 
-    id instance = [klass new];
-    if (![instance respondsToSelector:@selector(getTurboModule:)]) {
-      RCTLogError(@"Module provider %@ does not conform to RCTModuleProvider", moduleProviderName);
-      continue;
-    }
-
-    [dict setObject:instance forKey:key];
-  }
+    providers = dict;
+  });
 
-  return dict;
+  return providers;
 }
 
 @end

packages/react-native/scripts/codegen/templates/RCTModulesConformingToProtocolsProviderMM.template

@@ -11,23 +11,44 @@
 
 +(NSArray<NSString *> *)imageURLLoaderClassNames
 {
-  return @[
-    {imageURLLoaderClassNames}
-  ];
+  static NSArray<NSString *> *classNames = nil;
+  static dispatch_once_t onceToken;
+  
+  dispatch_once(&onceToken, ^{
+    classNames = @[
+      {imageURLLoaderClassNames}
+    ];
+  });
+  
+  return classNames;
 }
 
 +(NSArray<NSString *> *)imageDataDecoderClassNames
 {
-  return @[
-    {imageDataDecoderClassNames}
-  ];
+  static NSArray<NSString *> *classNames = nil;
+  static dispatch_once_t onceToken;
+  
+  dispatch_once(&onceToken, ^{
+    classNames = @[
+      {imageDataDecoderClassNames}
+    ];
+  });
+  
+  return classNames;
 }
 
 +(NSArray<NSString *> *)URLRequestHandlerClassNames
 {
-  return @[
-    {requestHandlersClassNames}
-  ];
+  static NSArray<NSString *> *classNames = nil;
+  static dispatch_once_t onceToken;
+  
+  dispatch_once(&onceToken, ^{
+    classNames = @[
+      {requestHandlersClassNames}
+    ];
+  });
+  
+  return classNames;
 }
 
 @end

packages/react-native/scripts/codegen/templates/RCTThirdPartyComponentsProviderMM.template

@@ -15,9 +15,16 @@
 
 + (NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *)thirdPartyFabricComponents
 {
-  return @{
+  static NSDictionary<NSString *, Class<RCTComponentViewProtocol>> *thirdPartyComponents = nil;
+  static dispatch_once_t nativeComponentsToken;
+
+  dispatch_once(&nativeComponentsToken, ^{
+    thirdPartyComponents = @{
 {thirdPartyComponentsMapping}
-  };
+    };
+  });
+
+  return thirdPartyComponents;
 }
 
 @end