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Getting Started

Click View on your Phone in your a0 project to generate a QR code that works with:

a0.dev App

iOS Testing
  • Opens directly if installed
  • Shows install option if not
  • Hot reloading enabled

Expo Go v52

Android Testing
  • Must use version 52
  • Same QR code works
  • Full hot reload support
Once scanned, the connection persists across different apps. You won’t need to rescan unless you refresh the page.

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Testing with the a0 App (iOS)

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Quick Setup

1

Get the QR Code

Click View on your Phone in your a0 project.
2

Scan with iPhone Camera

  • If you have a0 app → Opens immediately
  • If not → Shows App Store install link
3

Start Testing

Your app loads with hot reloading enabled. Save changes in the editor and they appear instantly.

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Testing with Expo Go v52 (Android)

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Setup

1

Install Expo Go v52

Download from the Expo Website and verify version 52 in app settings.
2

Scan the QR Code

Use the same QR code from View on your Phone - it works for both a0 app and Expo Go.
3

Test Your App

App loads with full hot reloading support.

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Limitations

Important: The a0 app does NOT support:
  • ❌ Payment processing (UI shows but transactions fail)
  • ❌ Ad networks
  • ❌ Some custom native modules
For testing payments or ads, you must test a native build.

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Hot Reloading

Both a0 app and Expo Go provide seamless hot reloading:
  1. Instant Updates: Save in editor → See changes immediately
  2. Persistent Connection: Switch between apps without rescanning
  3. State Preservation: Component state maintained during updates
  4. Error Recovery: Clear errors shown with stack traces
The hot reload connection stays active even when switching between different apps on your phone. Only a page refresh breaks the connection.

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Development Workflow

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Rapid Testing Cycle

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Testing Multiple Devices

You can test on multiple devices simultaneously:
  • Each device scans the same QR code
  • All devices update together
  • Test iOS and Android side-by-side

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Debugging

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Developer Menu

Shake your device or tap the screen with three fingers to access:
  • Reload - Refresh the app
  • Debug - Connect to debugger
  • Inspector - View component tree
  • Perf Monitor - See performance metrics

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Console Logs

// Logs appear in:
// 1. Browser console (if connected)
// 2. Device logs

console.log('Debug message');
console.warn('Warning');
console.error('Error details');

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Troubleshooting

  • Ensure that all your code is correct, this usually happens when there is an error
  • For Android, verify Expo Go is v52
  • Try refreshing and generating new QR
  • Open the project directly within the app instead of with the QR
  • Check error messages in console
  • Verify all imports are correct
  • Some web-only code may not work
  • Review device logs for details
This is expected behavior:
  • a0 app and Expo Go can’t process payments
  • UI will show but transactions fail
  • Build IPA/APK for payment testing

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Next Steps

Build for Production

Ready to test payments or ads? Build an IPA or APK with full native support.

Deploy Updates

Learn how to push updates to all your users instantly.