Deployment in React Native

Introduction

Deployment in React Native is the process of preparing your app for distribution and publishing it to the app stores. It involves different steps and tools depending on the platform you are targeting. For Android, you need to sign your app with a digital certificate, generate an upload key, update your Gradle files, and create an APK file. For iOS, you need to link libraries, run your app on a simulator, communicate with native modules, add app extensions, and submit your app to the App Store.

These steps ensure that your app is secure, optimized, and compliant with the platform requirements.

Deployment in Android

Digitally Signing Your Android App

Before you can publish your Android app, you need to sign it with a digital certificate. This certificate identifies the author of the app and ensures that the app has not been tampered with or modified after it was signed.

To sign your app, you need to use a tool called keytool that comes with the Java Development Kit (JDK). You can use this tool to generate a keystore file that contains your private key and public certificate. To generate a keystore file, run the following command in your terminal:

This command will prompt you to enter some information such as your name, organization, and password. Make sure to remember the password and the alias you used, as you will need them later. The command will also create a file called my-release-key.keystore in your current directory. This file is your keystore file and you should keep it in a safe place.

Generating an Upload Key

After you have generated your keystore file, you need to create an upload key that you will use to upload your app to the Google Play Console. The upload key is a separate key that is used only for uploading purposes and does not affect the signing of your app. To generate an upload key, run the following command in your terminal:

This command will prompt you to enter the password for your keystore file and then create a file called upload_certificate.pem in your current directory. This file is your upload key and you should upload it to the Google Play Console when you create a new app.

Updating Gradle Files

Next, you need to update your Gradle files to configure your app for release mode. Gradle is a build system that automates the tasks involved in building, testing, and deploying your app. To update your Gradle files, follow these steps:

1. Open the android/app/build.gradle file in your project directory and add the following code inside the android block:

This code defines a signing configuration for your release build using the keystore file and password you generated earlier. It also enables minification and obfuscation of your code using ProGuard, which reduces the size of your APK file and protects it from reverse engineering.

2. Open the android/gradle.properties file in your project directory and add the following code at the end of the file:

This code defines some variables that store the values of your keystore file, alias, and password. You can use these variables instead of hardcoding them in your build.gradle file.

3. Open the android/app/src/main/AndroidManifest.xml file in your project directory and make sure that the android and android attributes are set to the correct values for your app.

The version code is an integer that represents the internal version of your app, and the version name is a string that represents the user-visible version of your app. You should increment these values whenever you release a new version of your app.

Generating the APK Release Build

Now that you have updated your Gradle files, you are ready to generate the APK release build of your app. An APK file is a package that contains all the files and resources of your app. To generate the APK release build, run the following command in your terminal:

This command will run the Gradle tasks to build your app in release mode and create an APK file in the android/app/build/outputs/apk/release directory. The name of the APK file will be app-release.apk.

Testing the Release Build

Before you upload your APK file to the Google Play Console, you should test it on a real device or an emulator to make sure that it works as expected. To test your release build, follow these steps:

1. Connect your device to your computer via USB or launch an emulator

Run the following command in your terminal to install the APK file on your device or emulator:

2. Run the app on your device or emulator and check for any errors or bugs

Deployment in iOS

Linking Libraries

If you are using any third-party libraries or native modules in your React Native app, you need to link them to your iOS project. Linking is the process of connecting the native code of a library or module to your project so that it can be used by your app. There are two ways to link libraries or modules in iOS: manually or automatically.

Manually linking involves adding the library or module files to your Xcode project, setting up the header search paths, and linking the binary libraries. This method is more tedious and error-prone, but it gives you more control over how the library or module is integrated with your project.

Automatically linking involves using a tool called a react-native link that does all the steps for you. This method is easier and faster, but it may not work for some libraries or modules that require additional configuration. To link libraries or modules in iOS, follow these steps:

1. Open a terminal and navigate to your project directory

Run the following command to install the dependencies of your app:

2. Run the following command to link the libraries or modules that support automatic linking:

Alternatively, you can run the following commands to make sure all the dependencies are linked:

For the libraries or modules that do not support automatic linking, follow their installation instructions to link them manually.

3. Open the ios/<YourProjectName>.xcworkspace file in Xcode and check if the libraries or modules are linked correctly

Running on Simulator

Before you can publish your iOS app, you need to run it on a simulator to test its functionality and appearance. A simulator is a software application that mimics the behavior and features of a real device. To run your app on a simulator, follow these steps:

1. Open a terminal and navigate to your project directory

Run the following command to start the React Native packager:

2. Open another terminal and run the following command to launch your app on a simulator:

This command will open Xcode and launch a simulator with your app running on it. You can choose a different simulator by adding the --simulator flag with the name of the simulator you want to use. For example:

Test your app on the simulator and check for any errors or bugs. Communication between native and React Native One of the advantages of React Native is that it allows you to communicate with native code and access native features that are not available in JavaScript.

For example, you can use native modules to access device sensors, cameras, location, etc., or use native components to render native UI elements such as maps, video players, etc. To communicate between Native and React Native, you need to use two APIs: NativeModules and NativeEventEmitter.

• NativeModules is an API that allows you to call native methods from JavaScript. You can use this API to access native modules that are built-in to React Native, such as Alert, Clipboard, Geolocation, etc., or custom native modules that you create or install from third-party libraries. To use this API, you need to import the NativeModules object from react-native and access the native module by its name. For example:

• NativeEventEmitter is an API that allows you to subscribe to native events from JavaScript. You can use this API to listen to native events that are emitted by native modules or components, such as onPress, onScroll, onLayout, etc. To use this API, you need to import the NativeEventEmitter class from react-native and create an instance of it with the native module or component as the argument. Then, you can use the addListener method to register a callback function for the event you want to listen to. For example:

App Extensions

App extensions are a way to extend the functionality of your iOS app beyond the main app. They allow your app to interact with other apps or system features, such as widgets, keyboards, Siri, iMessage, etc. App extensions run as separate processes and have their bundle identifiers, provisioning profiles, and entitlements. To add an app extension to your React Native app, follow these steps:

• Open the ios/<YourProjectName>.xcworkspace file in Xcode and select your project in the project navigator.

• Click on the + button at the bottom of the targets list and choose New Target.

• Select the type of app extension you want to create and click Next.

• Enter a name and a bundle identifier for your app extension and click Finish.

• Xcode will create a new target and a new folder for your app extension in your project directory. You can edit the files and settings of your app extension as you would for any other iOS project.

• To use React Native in your app extension, you need to add the React Native dependencies to your app extension target. To do this, open the Podfile file in your project directory and add the following code at the end of the file:

• Run the following command in your terminal to install the pods:

To run your app extension, select it as the scheme in Xcode and choose a device or simulator to run it on. Publishing on the Apple App Store The final step of deploying your iOS app is to publish it on the Apple App Store. The App Store is a platform that allows users to discover and download apps for their iOS devices. To publish your app on the App Store, you need to follow these steps:

1. Create an Apple Developer account if you don’t have one already. You can sign up for an account at Apple Developer.