React Native is great when you are starting a new mobile app from scratch. However, it also works well for adding a single view or user flow to existing native applications. With a few steps, you can add new React Native based features, screens, views, etc.
The specific steps are different depending on what platform you're targeting.
- Android (Java)
- iOS (Objective-C)
- iOS (Swift)
The keys to integrating React Native components into your Android application are to:
- Set up React Native dependencies and directory structure.
- Add a
ReactRootViewto your Android app. This view will serve as the container for your React Native component.
- Start the React Native server and run your native application.
- Verify that the React Native aspect of your application works as expected.
Follow the React Native CLI Quickstart in the environment setup guide to configure your development environment for building React Native apps for Android.
1. Set up directory structure
To ensure a smooth experience, create a new folder for your integrated React Native project, then copy your existing Android project to an
Go to the root directory for your project and create a new
package.json file with the following contents:
Next, make sure you have installed the yarn package manager.
react-native packages. Open a terminal or command prompt, then navigate to the directory with your
package.json file and run:
This will print a message similar to the following (scroll up in the yarn output to see it):
This is OK, it means we also need to install React:
Yarn has created a new
node_modules/ to your
Adding React Native to your app
Add the React Native and JSC dependency to your app's
If you want to ensure that you are always using a specific React Native version in your native build, replace
+with an actual React Native version you've downloaded from
Add an entry for the local React Native and JSC maven directories to the top-level
build.gradle. Be sure to add it to the “allprojects” block, above other maven repositories:
Make sure that the path is correct! You shouldn’t run into any “Failed to resolve: com.facebook.react:react-native:0.x.x" errors after running Gradle sync in Android Studio.
Enable native modules autolinking
To use the power of autolinking, we have to apply it a few places. First add the following entry to
Next add the following entry at the very bottom of the
Next, make sure you have the Internet permission in your
If you need to access to the
DevSettingsActivity add to your
Cleartext Traffic (API level 28+)
Starting with Android 9 (API level 28), cleartext traffic is disabled by default; this prevents your application from connecting to the Metro bundler. The changes below allow cleartext traffic in debug builds.
1. Apply the
usesCleartextTraffic option to your Debug
This is not required for Release builds.
To learn more about Network Security Config and the cleartext traffic policy see this link.
Now we will actually modify the native Android application to integrate React Native.
The React Native component
The first bit of code we will write is the actual React Native code for the new "High Score" screen that will be integrated into our application.
1. Create a
First, create an empty
index.js file in the root of your React Native project.
index.js is the starting point for React Native applications, and it is always required. It can be a small file that
requires other file that are part of your React Native component or application, or it can contain all the code that is needed for it. In our case, we will put everything in
2. Add your React Native code
index.js, create your component. In our sample here, we will add a
<Text> component within a styled
3. Configure permissions for development error overlay
If your app is targeting the Android
API level 23 or greater, make sure you have the permission
android.permission.SYSTEM_ALERT_WINDOW enabled for the development build. You can check this with
Settings.canDrawOverlays(this);. This is required in dev builds because React Native development errors must be displayed above all the other windows. Due to the new permissions system introduced in the API level 23 (Android M), the user needs to approve it. This can be achieved by adding the following code to your Activity's in
onActivityResult() method (as shown in the code below) has to be overridden to handle the permission Accepted or Denied cases for consistent UX. Also, for integrating Native Modules which use
startActivityForResult, we need to pass the result to the
onActivityResult method of our
Let's add some native code in order to start the React Native runtime and tell it to render our JS component. To do this, we're going to create an
Activity that creates a
ReactRootView, starts a React application inside it and sets it as the main content view.
If you are targeting Android version <5, use the
AppCompatActivityclass from the
com.android.support:appcompatpackage instead of
If you are using a starter kit for React Native, replace the "HelloWorld" string with the one in your index.js file (it’s the first argument to the
Perform a “Sync Project files with Gradle” operation.
If you are using Android Studio, use
Alt + Enter to add all missing imports in your MyReactActivity class. Be careful to use your package’s
BuildConfig and not the one from the
We need set the theme of
Theme.AppCompat.Light.NoActionBar because some React Native UI components rely on this theme.
ReactInstanceManagercan be shared by multiple activities and/or fragments. You will want to make your own
ReactActivityand have a singleton holder that holds a
ReactInstanceManager. When you need the
ReactInstanceManager(e.g., to hook up the
ReactInstanceManagerto the lifecycle of those Activities or Fragments) use the one provided by the singleton.
Next, we need to pass some activity lifecycle callbacks to the
We also need to pass back button events to React Native:
invokeDefaultOnBackPressed method will be called. By default this finishes your
Finally, we need to hook up the dev menu. By default, this is activated by (rage) shaking the device, but this is not very useful in emulators. So we make it show when you press the hardware menu button (use
Ctrl + M if you're using Android Studio emulator):
Test your integration
You have now done all the basic steps to integrate React Native with your current application. Now we will start the Metro bundler to build the
index.bundle package and the server running on localhost to serve it.
1. Run the packager
To run your app, you need to first start the development server. To do this, run the following command in the root directory of your React Native project:
2. Run the app
Now build and run your Android app as normal.
Creating a release build in Android Studio
You can use Android Studio to create your release builds too! It’s as quick as creating release builds of your previously-existing native Android app. There’s one additional step, which you’ll have to do before every release build. You need to execute the following to create a React Native bundle, which will be included with your native Android app:
Don’t forget to replace the paths with correct ones and create the assets folder if it doesn’t exist.
Now, create a release build of your native app from within Android Studio as usual and you should be good to go!