Expo, EAS Build & OTA Updates

Managed vs Bare workflow

Managed workflow is the fastest way to start — Expo handles the native project, you write only JavaScript. The tradeoff: you can only use native capabilities that Expo’s SDK provides (or that have Expo config plugins).

Bare workflow is just a standard React Native project with Expo tooling layered on top. Full access to native code, any library, any config.

When to leave managed (eject)

You need to leave managed when:

• A native library requires custom native code with no config plugin
• You need to modify AppDelegate.swift, MainActivity.kt, or deep build config
• A required SDK or API isn’t in the Expo SDK and has no config plugin

Ejecting is now called “prebuild” — npx expo prebuild generates the native ios/ and android/ folders without changing your JS code. You keep Expo Router, Expo SDK, and EAS Build — you just now have full native control.

Expo Go — for development, not production

Expo Go is a pre-built RN runtime you install on your device. It lets you scan a QR code and instantly run your dev app — no compilation needed.

Limitation: it can only run Expo-managed apps using the Expo SDK. If your app has custom native code, Expo Go can’t run it — you need Expo Dev Client (a custom Expo Go you build yourself that includes your native dependencies).

EAS Build — cloud builds

EAS (Expo Application Services) Build runs your builds on Expo’s cloud servers — iOS and Android — without needing a Mac for iOS builds.

npx expo install eas-cli
eas login
eas build:configure          # generates eas.json

# Build for production
eas build --platform ios     # sends to App Store
eas build --platform android # generates .apk or .aab

# Build for testing (internal distribution)
eas build --platform all --profile preview

eas.json controls build profiles:

{
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal"
    },
    "preview": {
      "distribution": "internal"
    },
    "production": {}
  }
}

EAS Submit can also handle App Store and Play Store submissions:

eas submit --platform ios     # submits the latest build to App Store Connect

OTA Updates — what they can and can’t change

OTA (Over-The-Air) updates push JavaScript bundle changes to users without going through the App Store review process. Both EAS Update (Expo’s solution) and CodePush (Microsoft/App Center) work this way.

What OTA CAN update

• All JavaScript code — components, business logic, navigation
• Asset files that are bundled in JavaScript (images imported as require('./icon.png'))
• Third-party JS libraries

What OTA CANNOT update

• Native code (Swift, Kotlin, C++) — changes here always require a new binary
• Native dependencies — adding or updating a library with native code requires a store release
• App permissions — declared in Info.plist and AndroidManifest.xml
• App icon, splash screen — native assets
• The Expo SDK version itself

This is the critical constraint: OTA is for JS hotfixes, not architecture changes.

EAS Update setup

npx expo install expo-updates
eas update:configure

// In your app — check for updates on launch
import * as Updates from 'expo-updates';

async function checkForUpdates() {
  if (!Updates.isEmbeddedLaunch) return; // already on a downloaded update
  try {
    const update = await Updates.checkForUpdateAsync();
    if (update.isAvailable) {
      await Updates.fetchUpdateAsync();
      await Updates.reloadAsync(); // restart to apply
    }
  } catch (err) {
    console.error('Update check failed:', err);
  }
}

# Push an update
eas update --branch production --message "Fix login crash"

CodePush (Microsoft App Center)

import CodePush from 'react-native-code-push';

// Wrap the root component — checks and applies updates automatically
export default CodePush({
  checkFrequency: CodePush.CheckFrequency.ON_APP_RESUME,
  updateDialog: { title: 'Update Available', optionalInstallButtonLabel: 'Install' },
  installMode: CodePush.InstallMode.ON_NEXT_RESUME,
})(App);

The full CI/CD pipeline

Developer pushes code
        ↓
GitHub Actions / CI — run tests, type check, lint
        ↓
EAS Build (on merge to main) — build iOS + Android binaries
        ↓
EAS Submit — upload to TestFlight / Google Play Internal
        ↓
QA approval
        ↓
EAS Submit — production release
        ↓ (for JS-only hotfixes)
EAS Update / CodePush — push OTA update