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class=docMainContainer_a9sJ><div class="container padding-top--md padding-bottom--lg"><div class=row><div class="col docItemCol_Qr34"><div class=docItemContainer_tjFy><article><div class="tocCollapsible_wXna theme-doc-toc-mobile tocMobile_Ojys"><button type=button class="clean-btn tocCollapsibleButton_iI2p">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Using Codegen</h1></header> 5<p>This guide teaches how to:</p> 6<ul> 7<li>Configure <strong>Codegen</strong>.</li> 8<li>Invoke it manually for each platform.</li> 9</ul> 10<p>It also describes the generated code.</p> 11<h2 class="anchor anchorWithStickyNavbar_JmGV" id=prerequisites>Prerequisites<a href=#prerequisites class=hash-link aria-label="Direct link to Prerequisites" title="Direct link to Prerequisites">​</a></h2> 12<p>You always need a React Native app to generate the code properly, even when invoking the <strong>Codegen</strong> manually.</p> 13<p>The <strong>Codegen</strong> process is tightly coupled with the build of the app, and the scripts are located in the <code>react-native</code> NPM package.</p> 14<p>For the sake of this guide, create a project using the React Native CLI as follows:</p> 15<div class="language-bash codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>bash</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-bash codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token plain">npx @react-native-community/cli@latest init SampleApp </span><span class="token parameter variable" style=color:#cb4b16>--version</span><span class="token plain"> </span><span class="token number" style=color:#5a9bcf>0.76</span><span class="token plain">.0</span><br></span></code></pre></div></div> 16<p><strong>Codegen</strong> is used to generate the glue-code for your custom modules or components. See the guides for Turbo Native Modules and Fabric Native Components for more details on how to create them.</p> 17<h2 class="anchor anchorWithStickyNavbar_JmGV" id=configuring-codegen>Configuring <strong>Codegen</strong><a href=#configuring-codegen class=hash-link aria-label="Direct link to configuring-codegen" title="Direct link to configuring-codegen">​</a></h2> 18<p><strong>Codegen</strong> can be configured in your app by modifying the <code>package.json</code> file. <strong>Codegen</strong> is controlled by a custom field called <code>codegenConfig</code>.</p> 19<div class="language-json codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>package.json</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-json codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"codegenConfig"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"name"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;SpecName>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"type"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;types>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"jsSrcsDir"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;source_dir>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"android"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"javaPackageName"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;java.package.name>"</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"ios"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"modulesConformingToProtocol"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"RCTImageURLLoader"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;iOS-class-conforming-to-RCTImageURLLoader>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token comment" style=color:#93a1a1>// example from react-native-camera-roll: https://github.com/react-native-cameraroll/react-native-cameraroll/blob/8a6d1b4279c76e5682a4b443e7a4e111e774ec0a/package.json#L118-L127</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token comment" style=color:#93a1a1>// "RNCPHAssetLoader",</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>]</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"RCTURLRequestHandler"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;iOS-class-conforming-to-RCTURLRequestHandler>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token comment" style=color:#93a1a1>// example from react-native-camera-roll: https://github.com/react-native-cameraroll/react-native-cameraroll/blob/8a6d1b4279c76e5682a4b443e7a4e111e774ec0a/package.json#L118-L127</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token comment" style=color:#93a1a1>// "RNCPHAssetUploader",</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>]</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"RCTImageDataDecoder"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;iOS-class-conforming-to-RCTImageDataDecoder>"</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token comment" style=color:#93a1a1>// we don't have a good example for this, but it works in the same way. Pass the name of the class that implements the RCTImageDataDecoder. It must be a Native Module.</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"componentProvider"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"&lt;componentName>"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;iOS-class-implementing-the-component>"</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token punctuation" style=color:#657b83>,</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"modulesProvider"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"&lt;moduleName>"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token string" style=color:#8dc891>"&lt;iOS-class-implementing-the-RCTModuleProvider-protocol>"</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token punctuation" style=color:#657b83>,</span><br></span></code></pre></div></div> 20<p>You can add this snippet to your app and customize the various fields:</p> 21<ul> 22<li><code>name:</code> This is the name that will be used to create files containing your specs. As a convention, It should have the suffix <code>Spec</code>, but this is not mandatory.</li> 23<li><code>type</code>: the type of code we need to generate. Allowed values are <code>modules</code>, <code>components</code>, <code>all</code>.<!-- --> 24<ul> 25<li><code>modules:</code> use this value if you only need to generate code for Turbo Native Modules.</li> 26<li><code>components:</code> use this value if you only need to generate code for Native Fabric Components.</li> 27<li><code>all</code>: use this value if you have a mixture of components and modules.</li> 28</ul> 29</li> 30<li><code>jsSrcsDir</code>: this is the root folder where all your specs live.</li> 31<li><code>android.javaPackageName</code>: this is an Android specific setting to let <strong>Codegen</strong> generate the files in a custom package.</li> 32<li><code>ios</code>: the <code>ios</code> field is an object that can be used by app developers and library maintainers to provide some advanced functionalities. All the following fields are <strong>optional</strong>.<!-- --> 33<ul> 34<li><code>ios.modulesConformingToProtocol</code>: React Native offers some protocols that native modules can implement to customize some behaviors. These fields allow you to define the list of module that conforms to those protocols. These modules will be injected in the React Native runtime when the app starts.<!-- --> 35<ul> 36<li><code>ios.modulesConformingToProtocol.RCTImageURLLoader</code>: list of iOS native module that implements the <a href=https://github.com/facebook/react-native/blob/00d5caee9921b6c10be8f7d5b3903c6afe8dbefa/packages/react-native/Libraries/Image/RCTImageURLLoader.h#L26-L81 target=_blank rel="noopener noreferrer"><code>RCTImageURLLoader</code> protocol</a>. You need to pass the class names of iOS classes that implements the <code>RCTImageURLLoader</code>. They must be Native Modules.</li> 37<li><code>ios.modulesConformingToProtocol.RCTURLRequestHandler</code>: list of iOS native module that implements the <a href=https://github.com/facebook/react-native/blob/00d5caee9921b6c10be8f7d5b3903c6afe8dbefa/packages/react-native/React/Base/RCTURLRequestHandler.h#L11-L52 target=_blank rel="noopener noreferrer"><code>RCTURLRequestHandler</code> protocol</a>. You need to pass the class names of iOS classes that implements the <code>RCTURLRequestHandler</code>. They must be Native Modules.</li> 38<li><code>ios.modulesConformingToProtocol.RCTImageDataDecoder</code>: list of iOS native module that implements the <a href=https://github.com/facebook/react-native/blob/00d5caee9921b6c10be8f7d5b3903c6afe8dbefa/packages/react-native/Libraries/Image/RCTImageDataDecoder.h#L15-L53 target=_blank rel="noopener noreferrer"><code>RCTImageDataDecoder</code> protocol</a>. You need to pass the class names of iOS classes that implements the <code>RCTImageDataDecoder</code>. They must be Native Modules.</li> 39</ul> 40</li> 41<li><code>ios.componentProvider</code>: this field is a map used to generate the association between a custom JS React component and the native class that implements it. The key of the map is the JS name of the component (for example <code>TextInput</code>), and the value is the iOS class that implements the component (for example <code>RCTTextInput</code>).</li> 42<li><code>ios.modulesProvider</code>: this field is a map used to generate the association between a custom JS Native Module and the native class that can provide it. The key of the map is the JS name of the module (for example <code>NativeLocalStorage</code>), and the value is the iOS class that implements the <a href=https://github.com/facebook/react-native/blob/0.79-stable/packages/react-native/ReactCommon/react/nativemodule/core/platform/ios/ReactCommon/RCTTurboModule.h#L179-L190 target=_blank rel="noopener noreferrer"><code>RCTModuleProvider</code> protocol</a>. For Objective-C modules, the class implementing the <a href=https://github.com/facebook/react-native/blob/0.79-stable/packages/react-native/ReactCommon/react/nativemodule/core/platform/ios/ReactCommon/RCTTurboModule.h#L192-L200 target=_blank rel="noopener noreferrer"><code>RCTTurboModule</code> protocol</a> is also implementing the <code>RCTModuleProvider</code> protocol. For more information, looks at the <a href=/docs/next/the-new-architecture/pure-cxx-modules>Cross-Platform Native Modules (C++) guide</a>.</li> 43</ul> 44</li> 45</ul> 46<p>When <strong>Codegen</strong> runs, it searches among all the dependencies of the app, looking for JS files that respects some specific conventions, and it generates the required code:</p> 47<ul> 48<li>Turbo Native Modules require that the spec files are prefixed with <code>Native</code>. For example, <code>NativeLocalStorage.ts</code> is a valid name for a spec file.</li> 49<li>Native Fabric Components require that the spec files are suffixed with <code>NativeComponent</code>. For example, <code>WebViewNativeComponent.ts</code> is a valid name for a spec file.</li> 50</ul> 51<h2 class="anchor anchorWithStickyNavbar_JmGV" id=running-codegen>Running <strong>Codegen</strong><a href=#running-codegen class=hash-link aria-label="Direct link to running-codegen" title="Direct link to running-codegen">​</a></h2> 52<p>The rest of this guide assumes that you have a Native Turbo Module, a Native Fabric Component or both already set up in your project. We also assume that you have valid specification files in the <code>jsSrcsDir</code> specified in the <code>package.json</code>.</p> 53<h3 class="anchor anchorWithStickyNavbar_JmGV" id=android>Android<a href=#android class=hash-link aria-label="Direct link to Android" title="Direct link to Android">​</a></h3> 54<p><strong>Codegen</strong> for Android is integrated with the React Native Gradle Plugin (RNGP). The RNGP contains a task that can be invoked that reads the configurations defined in the <code>package.json</code> file and execute <strong>Codegen</strong>. To run the gradle task, first navigate inside the <code>android</code> folder of your project. Then run:</p> 55<div class="language-bash codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>bash</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-bash codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token plain">./gradlew generateCodegenArtifactsFromSchema</span><br></span></code></pre></div></div> 56<p>This task invokes the <code>generateCodegenArtifactsFromSchema</code> command on all the imported projects of the app (the app and all the node modules which are linked to it). It generates the code in the corresponding <code>node_modules/&lt;dependency></code> folder. For example, if you have a Fabric Native Component whose Node module is called <code>my-fabric-component</code>, the generated code is located in the <code>SampleApp/node_modules/my-fabric-component/android/build/generated/source/codegen</code> path. For the app, the code is generated in the <code>android/app/build/generated/source/codegen</code> folder.</p> 57<h4 class="anchor anchorWithStickyNavbar_JmGV" id=the-generated-code>The Generated Code<a href=#the-generated-code class=hash-link aria-label="Direct link to The Generated Code" title="Direct link to The Generated Code">​</a></h4> 58<p>After running the gradle command above, you will find the codegen code in the <code>SampleApp/android/app/build</code> folder. The structure will look like this:</p> 59<div class="language-tsx codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-tsx codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token plain">build</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain">└── generated</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> └── source</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> └── codegen</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> ├── java</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> │ └── com</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> │ ├── facebook</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> │ │ └── react</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> │ │ └── viewmanagers</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> │ │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>nativeComponent</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">ManagerDelegate.java</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ │ └── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>nativeComponent</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">ManagerInterface.java</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── sampleapp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── NativeLocalStorageSpec.java</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── jni</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">-generated.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── CMakeLists.txt</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── react</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── renderer</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── components</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">JSI-generated.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── ComponentDescriptors.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── ComponentDescriptors.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── EventEmitters.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── EventEmitters.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── Props.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── Props.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── ShadowNodes.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── ShadowNodes.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── States.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── States.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── schema.json</span><br></span></code></pre></div></div> 60<p>The generated code is split in two folders:</p> 61<ul> 62<li><code>java</code> which contains the platform specific code</li> 63<li><code>jni</code> which contains the C++ code required to let JS and Java interact correctly.</li> 64</ul> 65<p>In the <code>java</code> folder, you can find the Fabric Native component generated code in the <code>com/facebook/viewmanagers</code> subfolder.</p> 66<ul> 67<li>the <code>&lt;nativeComponent>ManagerDelegate.java</code> contains the methods that the <code>ViewManager</code> can call on the custom Native Component</li> 68<li>the <code>&lt;nativeComponent>ManagerInterface.java</code> contains the interface of the <code>ViewManager</code>.</li> 69</ul> 70<p>In the folder whose name was set up in the <code>codegenConfig.android.javaPackageName</code>, instead, you can find the abstract class that a Turbo Native Module has to implement to carry out its tasks.</p> 71<p>In the <code>jni</code> folder, finally, there is all the boilerplate code to connect JS to Android.</p> 72<ul> 73<li><code>&lt;codegenConfig.name>.h</code> this contains the interface of your custom C++ Turbo Native Modules.</li> 74<li><code>&lt;codegenConfig.name>-generated.cpp</code> this contains the glue code of your custom C++ Turbo Native Modules.</li> 75<li><code>react/renderer/components/&lt;codegenConfig.name></code>: this folder contains all the glue-code required by your custom component.</li> 76</ul> 77<p>This structure has been generated by using the value <code>all</code> for the <code>codegenConfig.type</code> field. If you use the value <code>modules</code>, expect to see no <code>react/renderer/components/</code> folder. If you use the value <code>components</code>, expect not to see any of the other files.</p> 78<h3 class="anchor anchorWithStickyNavbar_JmGV" id=ios>iOS<a href=#ios class=hash-link aria-label="Direct link to iOS" title="Direct link to iOS">​</a></h3> 79<p><strong>Codegen</strong> for iOS relies on some Node scripts that are invoked during the build process. The scripts are located in the <code>SampleApp/node_modules/react-native/scripts/</code> folder.</p> 80<p>The main script is the <code>generate-codegen-artifacts.js</code> script. To invoke the script, you can run this command from the root folder of your app:</p> 81<div class="language-bash codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>bash</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-bash codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token function" style=color:#79b6f2>node</span><span class="token plain"> node_modules/react-native/scripts/generate-codegen-artifacts.js</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain" style=display:inline-block></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain">Usage: generate-codegen-artifacts.js </span><span class="token parameter variable" style=color:#cb4b16>-p</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">path to app</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>-t</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">target platform</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>-o</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">output path</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain" style=display:inline-block></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain">Options:</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>--help</span><span class="token plain"> Show </span><span class="token builtin class-name" style=color:#fac863>help</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">boolean</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>--version</span><span class="token plain"> Show version number </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">boolean</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> -p, </span><span class="token parameter variable" style=color:#cb4b16>--path</span><span class="token plain"> Path to the React Native project root. </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">required</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> -t, </span><span class="token parameter variable" style=color:#cb4b16>--targetPlatform</span><span class="token plain"> Target platform. Supported values: </span><span class="token string" style=color:#8dc891>"android"</span><span class="token plain">, </span><span class="token string" style=color:#8dc891>"ios"</span><span class="token plain">,</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token string" style=color:#8dc891>"all"</span><span class="token builtin class-name" style=color:#fac863>.</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token plain">required</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> -o, </span><span class="token parameter variable" style=color:#cb4b16>--outputPath</span><span class="token plain"> Path where generated artifacts will be output to.</span><br></span></code></pre></div></div> 82<p>where:</p> 83<ul> 84<li><code>--path</code> is the path to the root folder of your app.</li> 85<li><code>--outputPath</code> is the destination where <strong>Codegen</strong> will write the generated files.</li> 86<li><code>--targetPlatform</code> is the platform you'd like to generate the code for.</li> 87</ul> 88<h4 class="anchor anchorWithStickyNavbar_JmGV" id=the-generated-code-1>The Generated Code<a href=#the-generated-code-1 class=hash-link aria-label="Direct link to The Generated Code" title="Direct link to The Generated Code">​</a></h4> 89<p>Running the script with these arguments:</p> 90<div class="language-shell codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>shell</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-shell codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token function" style=color:#79b6f2>node</span><span class="token plain"> node_modules/react-native/scripts/generate-codegen-artifacts.js </span><span class="token punctuation" style=color:#657b83>\</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>--path</span><span class="token plain"> </span><span class="token builtin class-name" style=color:#fac863>.</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>\</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>--outputPath</span><span class="token plain"> ios/ </span><span class="token punctuation" style=color:#657b83>\</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token parameter variable" style=color:#cb4b16>--targetPlatform</span><span class="token plain"> ios</span><br></span></code></pre></div></div> 91<p>Will generate these files in the <code>ios/build</code> folder:</p> 92<div class="language-tsx codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-tsx codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token plain">build</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain">└── generated</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> └── ios</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">-generated.mm</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">JSI-generated.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text">JSI.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── FBReactNativeSpec</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ ├── FBReactNativeSpec-generated.mm</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> │ └── FBReactNativeSpec.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── FBReactNativeSpecJSI-generated.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── FBReactNativeSpecJSI.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── RCTModulesConformingToProtocolsProvider.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── RCTModulesConformingToProtocolsProvider.mm</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── react</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── renderer</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── components</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── </span><span class="token tag punctuation" style=color:#657b83>&lt;</span><span class="token tag" style=color:#fc929e>codegenConfig.name</span><span class="token tag punctuation" style=color:#657b83>></span><span class="token plain-text"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── ComponentDescriptors.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── ComponentDescriptors.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── EventEmitters.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── EventEmitters.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── Props.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── Props.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── RCTComponentViewHelpers.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── ShadowNodes.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── ShadowNodes.h</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> ├── States.cpp</span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain-text"> └── States.h</span><br></span></code></pre></div></div> 93<p>Part of these generated files are used by React Native in the Core. Then there is a set of files which contains the same name you specified in the package.json <code>codegenConfig.name</code> field.</p> 94<ul> 95<li><code>&lt;codegenConfig.name>/&lt;codegenConfig.name>.h</code>: this contains the interface of your custom iOS Turbo Native Modules.</li> 96<li><code>&lt;codegenConfig.name>/&lt;codegenConfig.name>-generated.mm</code>: this contains the glue code of your custom iOS Turbo Native Modules.</li> 97<li><code>&lt;codegenConfig.name>JSI.h</code>: this contains the interface of your custom C++ Turbo Native Modules.</li> 98<li><code>&lt;codegenConfig.name>JSI-generated.h</code>: this contains the glue code of your custom C++ Turbo Native Modules.</li> 99<li><code>react/renderer/components/&lt;codegenConfig.name></code>: this folder contains all the glue-code required by your custom component.</li> 100</ul> 101<p>This structure has been generated by using the value <code>all</code> for the <code>codegenConfig.type</code> field. If you use the value <code>modules</code>, expect to see no <code>react/renderer/components/</code> folder. If you use the value <code>components</code>, expect not to see any of the other files.</div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class=editButtons_t0bR><a href=https://github.com/facebook/react-native-website/edit/main/docs/the-new-architecture/using-codegen.md target=_blank rel="noopener noreferrer" class=theme-edit-this-page><svg fill=currentColor height=20 width=20 viewBox="0 0 40 40" class=iconEdit_bHB7 aria-hidden=true><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"/></g></svg>Edit page for next release</a><a href=https://github.com/facebook/react-native-website/edit/main/website/versioned_docs/version-0.79/the-new-architecture/using-codegen.md target=_blank rel="noopener noreferrer" class=theme-edit-this-page><svg fill=currentColor height=20 width=20 viewBox="0 0 40 40" class=iconEdit_bHB7 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