---
modificationDate: June 26, 2026
title: iOS App Extensions
description: Learn how to use app extensions with EAS Build to add custom functionality.
---

<AgentInstructions>

## Submitting Feedback

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## Navigation

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Pages in this section:
- [Build lifecycle hooks](https://docs.expo.dev/build-reference/npm-hooks.md)
- [Using private npm packages](https://docs.expo.dev/build-reference/private-npm-packages.md)
- [Git submodules](https://docs.expo.dev/build-reference/git-submodules.md)
- [Using npm cache with Yarn 1 (Classic)](https://docs.expo.dev/build-reference/npm-cache-with-yarn.md)
- [Set up EAS Build with a monorepo](https://docs.expo.dev/build-reference/build-with-monorepos.md)
- [Build APKs for Android Emulators and devices](https://docs.expo.dev/build-reference/apk.md)
- [Build for iOS Simulators](https://docs.expo.dev/build-reference/simulators.md)
- [App version management](https://docs.expo.dev/build-reference/app-versions.md)
- [Troubleshoot build errors and crashes](https://docs.expo.dev/build-reference/troubleshooting.md)
- [Install app variants on the same device](https://docs.expo.dev/build-reference/variants.md)
- [iOS capabilities](https://docs.expo.dev/build-reference/ios-capabilities.md)
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- [Cache dependencies](https://docs.expo.dev/build-reference/caching.md)
- [Android build process](https://docs.expo.dev/build-reference/android-builds.md)
- [iOS build process](https://docs.expo.dev/build-reference/ios-builds.md)
- [Configuration process](https://docs.expo.dev/build-reference/build-configuration.md)
- [Server infrastructure](https://docs.expo.dev/build-reference/infrastructure.md)
- [iOS App Extensions](https://docs.expo.dev/build-reference/app-extensions.md) (this page)
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Full documentation tree: [llms.txt](https://docs.expo.dev/llms.txt)

</AgentInstructions>

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# iOS App Extensions

Learn how to use app extensions with EAS Build to add custom functionality.

App extensions let you extend custom functionality and content beyond your app and make it available to users while they're interacting with other apps or iOS system functionality. EAS Build provides affordances for including app extensions in both [existing React Native projects](/bare/overview.md) and projects that use [Continuous Native Generation (CNG)](/workflow/continuous-native-generation.md).

## CNG projects (experimental support)

A typical, simple project that uses Continuous Native Generation (CNG) has a single application target and no app extensions. You can add an app extension to your project by writing a [config plugin](/config-plugins/introduction.md) (or using a library that creates an extension with its own config plugin). Config plugins let you add targets to the Xcode project that is generated during the "Prebuild" phase of a build job.

Declaring app extensions with `extra.eas.build.experimental.ios.appExtensions` in your app config makes it possible for EAS CLI to know what app extensions exist _before the build starts_ (before the Xcode project has been generated) to ensure that the required credentials are generated and validated. Config plugins are also able to modify the app config, and in most cases, if you are using a library that adds an extension then the config plugin will also add the required configuration to declare the extension in your app config. If you are writing a library, we recommend that you consider this. The following is an example of what this would look like if it were declared directly in **app.json**:

```json
{
  "expo": {
    ...
    "extra": {
      "eas": {
        "build": {
          "experimental": {
            "ios": {
              "appExtensions": [
                {
                  "targetName": "myappextension",
                  "bundleIdentifier": "com.myapp.extension",
                  "entitlements": {
                    "com.apple.example": "entitlement value"
                  }
                }
              ]
            }
          }
        }
      }
    }
  }
}
```

## Existing React Native projects

When you build an existing React Native project, EAS CLI will automatically detect app extensions configured in your Xcode project and generate all necessary credentials for each target, or you can provide them in **credentials.json** For more information, see [Multi target project](/app-signing/local-credentials.md#multi-target-project).