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React Native Academy · Lesson

Running on Device and Emulator

Launch your app on a physical device with Expo Go and on an emulator, then learn how to reload and inspect changes in real time.

Starting the Development Server

To run your app, go to its folder and run npx expo start. That launches Metro and shows a QR code. Keep your phone and computer on the same Wi-Fi for it to connect.

# Start the Expo development server
cd MyFirstApp
npx expo start

# Force iOS Simulator directly
npx expo start --ios

# Force Android Emulator directly
npx expo start --android

# Start in web browser mode
npx expo start --web

Running on iOS Simulator

With Metro running, press i to launch the iOS Simulator. The first load installs Expo Go and takes a moment; after that it's fast. macOS only, sorry. 🍎

# With Metro running, press 'i' in the terminal
# Or launch a specific simulator:
xcrun simctl boot 'iPhone 15 Pro'

# List available devices
xcrun simctl list devices

# Open the Simulator app
open -a Simulator

All lessons in this course

  1. Installing Node, Expo CLI, and Simulators
  2. Creating Your First Expo Project
  3. Running on Device and Emulator
  4. Understanding the Project Structure
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