Publishing and Deployment (EAS)

# CHAPTER 29

Publishing and Deployment (EAS) #

1. Introduction #

2. Learning Objectives #

• Understand the difference between Expo Go and a standalone binary.

• Configure app.json for production (Icons, Splash Screens, Bundle IDs).

• Install and configure the EAS CLI.

• Execute an Android cloud build to generate an APK/AAB.

• Execute an iOS cloud build to generate an IPA.

3. Preparing app.json (The Blueprint) #

{
  "expo": {
    "name": "My Awesome App",
    "slug": "my-awesome-app",
    "version": "1.0.0",
    "icon": "./assets/icon.png", // Must be exactly 1024x1024
    "splash": {
      "image": "./assets/splash.png",
      "resizeMode": "contain",
      "backgroundColor": "#ffffff"
    },
    "ios": {
      "bundleIdentifier": "com.mycompany.myawesomeapp" // CRITICAL for Apple
    },
    "android": {
      "package": "com.mycompany.myawesomeapp", // CRITICAL for Google
      "adaptiveIcon": {
        "foregroundImage": "./assets/adaptive-icon.png",
        "backgroundColor": "#ffffff"
      }
    }
  }
}

4. What is EAS Build? #

5. Installing the EAS CLI #

npm install -g eas-cli

Once installed, log into your Expo account:

eas login

6. Configuring the Project for EAS #

eas build:configure

This generates an eas.json file. This file contains the "profiles" (recipes) for your builds. To build an Android .apk file that you can install directly on a phone without going through the Play Store, add a preview profile:

{
  "build": {
    "preview": {
      "android": {
        "buildType": "apk"
      }
    },
    "production": {}
  }
}

7. Building for Android #

eas build -p android --profile preview

• EAS will upload your code.

• It will automatically generate a secure Android Keystore (cryptographic signature) for you.

• You will be given a URL to watch the build progress.

• Wait 10-15 minutes. When it finishes, download the .apk file and drag it onto your Android phone to install your standalone app!

8. Building for iOS (Apple App Store) #

To generate an iOS IPA file:

eas build -p ios

• EAS will prompt you to log into your Apple Developer Account.

• It will automatically manage all the horrific certificates, provisioning profiles, and push notification keys.

• Wait 15-20 minutes. Download the .ipa file, or instruct EAS to submit it directly to TestFlight!

9. Visual Learning: The EAS Architecture #

[ Your Laptop (JS Code) ]
          |
    (eas build -p android)
          v
[ Expo Cloud Server (Linux) ] -> Compiles Java/Kotlin -> [ Outputs .APK ]
          |
    (eas build -p ios)
          v
[ Expo Cloud Server (Mac OS) ] -> Compiles Swift/Obj-C -> [ Outputs .IPA ]

10. Common Mistakes #

• Ignoring Bundle Identifiers: If you do not change the ios.bundleIdentifier or android.package in app.json before building, Expo will generate a random one for you. If you later upload an update to the App Store with a *different* identifier, Apple and Google will reject it, claiming it is a completely different app. Set your bundle identifier (e.g., com.yourname.appname) ONCE and never touch it again.

11. Best Practices #

• Over-The-Air (OTA) Updates: What if you publish your app, users download it, and you realize there is a typo on the home screen? You do NOT need to run a new EAS build and wait for Apple to review it! Because React Native runs JavaScript, you can use EAS Update (eas update) to instantly beam the new JavaScript code directly to users' phones over the internet, instantly fixing the typo!

12. Practice Exercises #

1. 1. What critical JSON file must be edited to define the application's visual App Icon and Splash Screen before executing a cloud build?

1. 2. What EAS command line instruction is used to initiate the compilation process for an Android device?

13. MCQs with Answers #

14. Interview Questions #

• Q: Explain the mechanical difference between running an application within the "Expo Go" sandbox versus compiling a standalone native binary via EAS.

• Q: Detail the purpose of the bundleIdentifier (iOS) and package name (Android) in the app.json configuration. What are the severe consequences of changing this identifier after the application has been published to the stores?

• Q: Describe the mechanism of Over-The-Air (OTA) updates utilizing EAS Update. How does the architecture of React Native (a JavaScript bridge) technically allow code to be updated without compiling a new binary or passing through App Store review?

15. FAQs #

16. Summary #

17. Next Chapter Recommendation #