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How Live Preview Works

MobileCoder provides a live preview of your app that updates in real-time as the AI builds your code. You can test your app directly in the browser or on your physical device. The preview runs in a cloud sandbox powered by Expo, giving you an authentic mobile experience without needing to install any development tools locally.

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Testing in the Browser

The browser preview shows your app in a simulated phone frame. This is the fastest way to see changes and test basic functionality. Browser preview is great for:
  • Quick visual checks
  • Testing navigation flows
  • Verifying layout and styling
  • Rapid iteration
Some native features may not work in the browser preview. For the most accurate testing, use the Expo Go app on your physical device.

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Testing on Your Device with Expo Go

For the most accurate testing experience, scan the QR code to open your app in Expo Go on your phone.
1

Install Expo Go

Download the Expo Go app from the App Store (iOS) or Google Play (Android).
2

Scan the QR Code

In MobileCoder, click the QR code icon in the preview panel. Use your phone’s camera (iOS) or the Expo Go app (Android) to scan the code.
3

Test Your App

Your app will open in Expo Go with full native functionality. Changes made in MobileCoder will automatically refresh in the app.

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Preview States

The preview panel shows the current state of your sandbox:

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Sandbox Expiration and Auto-Resume

To save resources, MobileCoder pauses sandboxes after a period of inactivity (typically 20 minutes). When you return to your project:
  1. The sandbox will automatically resume
  2. Your code is restored from the saved state
  3. The preview will be available again in a few seconds
Your code is automatically saved to GitHub, so you never lose your work even if the sandbox expires.

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Preview Limitations

While the live preview is powerful, there are some limitations to be aware of:
  • Native modules: Some native iOS/Android features may not work in the browser preview
  • Push notifications: Require a physical device and proper setup
  • Camera/sensors: Hardware features require a physical device
  • Performance: The browser preview may be slower than a native build
For production testing, we recommend exporting your code and building a native app.

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Troubleshooting

Try refreshing the page or clicking the restart button in the preview panel. If the issue persists, check if the AI is still working on your code.
Make sure you have Expo Go installed. On iOS, use the native camera app. On Android, use the Expo Go app’s scanner.
Click anywhere in the preview panel or send a new message to resume your sandbox.

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Need more help?

Still have questions? Contact us at [email protected].