React Native Setup Expert (2025)

Expert in React Native 0.83+ and Expo SDK 54+ environment configuration across macOS, Windows, and Linux. Specializes in New Architecture setup, EAS Build configuration, and development environment optimization.

What I Know

Prerequisites & Installation (2025 Requirements)

Node.js & npm

• Node.js 20.x or later required (Node 18 EOL April 2025)
• Node.js 22 LTS recommended for best performance
• Version verification: node --version && npm --version
• Package managers: npm, yarn, pnpm, bun all supported
• Corepack for yarn: corepack enable && corepack prepare yarn@stable --activate

Xcode (macOS - iOS Development)

• Xcode 16.1 or later required (minimum for RN 0.83)
• Xcode 26 recommended for iOS Liquid Glass support
• Command line tools: xcode-select --install
• License acceptance: sudo xcodebuild -license accept
• iOS 15.1+ deployment target (minimum supported)
• iOS 18+ for latest features, iOS 26 for Liquid Glass

Android Studio (Android Development)

• Android Studio Ladybug or later (2024.2.1+)
• Required SDK components:
  • Android SDK Platform 35 (API level 35)
  • Android SDK Build-Tools 35.0.0
  • Android Emulator
  • Android SDK Platform-Tools
  • NDK 27.1.12297006 (for native modules)
  • CMake 3.22.1+ (for Turbo Modules)
• compileSdkVersion 35, targetSdkVersion 35, minSdkVersion 24
• ANDROID_HOME environment variable setup
• Edge-to-edge display support (Android 15+)

Watchman

• Installation via Homebrew (macOS): brew install watchman
• Purpose: File watching for fast refresh with Metro
• Critical for large codebases
• Cache clearing: watchman watch-del-all

Environment Configuration

iOS Setup

• CocoaPods 1.15+ installation: sudo gem install cocoapods
• Pod install with New Architecture: RCT_NEW_ARCH_ENABLED=1 pod install
• Xcode project configuration for Fabric
• Provisioning profiles and certificates
• iOS Simulator management
• Device selection: xcrun simctl list devices
• Liquid Glass testing requires iOS 26 simulator

Android Setup

• Gradle 8.10+ (bundled with Android Studio Ladybug)
• Android SDK path configuration
• Environment variables (ANDROID_HOME, PATH)
• AVD creation with API 35 images
• Emulator with edge-to-edge support
• ADB troubleshooting
• New Architecture: newArchEnabled=true in gradle.properties

Metro Bundler

• Port 8081 configuration
• Cache clearing: npx react-native start --reset-cache
• Metro config for New Architecture
• Symlink support for monorepos
• Custom resolver configuration

EAS Build Setup (Expo)

• Install EAS CLI: npm install -g eas-cli
• Login: eas login
• Configure: eas build:configure
• Development builds for custom native code
• EAS Update for OTA updates

Common Setup Issues

"Command not found" Errors

• PATH configuration for Node, Android SDK, Xcode tools
• Shell profile updates (.zshrc, .bash_profile)
• Symlink issues with nvm/fnm

SDK Not Found

• SDK path verification: echo $ANDROID_HOME
• Environment variable troubleshooting
• SDK Manager reinstallation
• NDK path for native modules

Pod Install Failures

• CocoaPods version issues (requires 1.15+)
• Ffi gem compilation errors on Apple Silicon
• Ruby version compatibility (use system Ruby or rbenv)
• New Architecture pod failures: clean and rebuild
• pod deintegrate && pod install strategy

Build Failures

• Clean build strategies (see Pro Tips)
• Dependency conflicts with New Architecture
• Native module compilation errors
• Xcode derived data clearing
• Gradle cache corruption

New Architecture Issues

• Turbo Module not found: check codegen ran
• Fabric component not rendering: verify native setup
• Bridge module compatibility: use interop layer

When to Use This Skill

Ask me when you need help with:

• Initial React Native 0.83+ environment setup
• Installing and configuring Xcode 16.1+ or Android Studio Ladybug
• Setting up iOS simulators or Android emulators
• Troubleshooting "Command not found" errors
• Resolving SDK path or ANDROID_HOME issues
• Fixing CocoaPods installation problems
• Clearing Metro bundler cache
• Configuring development environment variables
• Troubleshooting build failures
• Setting up watchman for file watching
• Verifying development environment prerequisites
• EAS Build configuration and troubleshooting
• New Architecture setup and migration
• Development build creation for custom native code
• Hermes V1 experimental setup

Quick Setup Commands

iOS (macOS)

# Install Xcode command line tools
xcode-select --install

# Accept Xcode license
sudo xcodebuild -license accept

# Install CocoaPods (1.15+ required)
sudo gem install cocoapods

# Install watchman
brew install watchman

# Verify setup
xcodebuild -version  # Should be 16.1+
pod --version        # Should be 1.15+
watchman version

Android (All Platforms)

# Verify Android setup
echo $ANDROID_HOME
adb --version
emulator -version

# Verify SDK version
$ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --list | grep "platforms;android-35"

# List available emulators
emulator -list-avds

# List connected devices
adb devices

React Native CLI Project

# Create new React Native project (New Architecture enabled by default)
npx @react-native-community/cli init MyProject

# Navigate to project
cd MyProject

# Install iOS dependencies with New Architecture
cd ios && RCT_NEW_ARCH_ENABLED=1 pod install && cd ..

# Start Metro bundler
npm start

# Run on iOS (separate terminal)
npm run ios

# Run on Android (separate terminal)
npm run android

Expo Project (Recommended)

# Create new Expo project
npx create-expo-app@latest MyProject

# Navigate to project
cd MyProject

# Start development server
npx expo start

# Create development build (for custom native code)
npx expo install expo-dev-client
eas build --profile development --platform ios
eas build --profile development --platform android

Pro Tips

1. Clean Builds: When in doubt, clean everything

   # iOS (nuclear option)
   cd ios && rm -rf build Pods Podfile.lock && pod install && cd ..
   
   # Android
   cd android && ./gradlew clean && cd ..
   
   # Metro + Watchman
   watchman watch-del-all
   npx react-native start --reset-cache
   
   # Expo
   npx expo start --clear
   

2. Environment Variables: Always verify environment variables after changes

   # Add to ~/.zshrc or ~/.bash_profile
   export ANDROID_HOME=$HOME/Library/Android/sdk
   export PATH=$PATH:$ANDROID_HOME/emulator
   export PATH=$PATH:$ANDROID_HOME/platform-tools
   export PATH=$PATH:$ANDROID_HOME/cmdline-tools/latest/bin
   
   # Reload shell
   source ~/.zshrc
   

3. Simulator Management: List and boot specific devices

   # iOS
   xcrun simctl list devices
   xcrun simctl boot "iPhone 16 Pro"
   
   # Android (API 35 for edge-to-edge)
   emulator -list-avds
   emulator -avd Pixel_8_API_35
   

4. Quick Health Check: Verify entire environment

   node --version      # Should be 20+
   npm --version       # npm
   xcodebuild -version # Should be 16.1+
   pod --version       # Should be 1.15+
   adb --version       # Android tools
   watchman version    # Watchman
   eas --version       # EAS CLI (Expo)
   

5. EAS Build Configuration: Essential eas.json

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

6. Hermes V1 (Experimental): Enable next-gen engine

   // metro.config.js
   module.exports = {
     transformer: {
       hermesParser: true,
     },
   };
   

   # Verify Hermes is running
   # In app: global.HermesInternal !== undefined
   

Version Compatibility Matrix (2025)

Integration with SpecWeave

This skill integrates with SpecWeave's increment workflow:

• Use during /sw:increment planning for environment setup tasks
• Reference in tasks.md for setup-related acceptance criteria
• Include in spec.md for mobile-specific prerequisites
• Document setup issues in increment reports/ folder
• Use mobile-architect agent for architecture decisions