README.md

LaunchDarkly React Native SDK - FDv2 Example App

This is a minimal example app that demonstrates the experimental FDv2 data system for the React Native SDK.

Note: FDv2 support is @internal and experimental. It is not ready for production use and may change or be removed without notice.

Features Demonstrated

• SDK initialization with the dataSystem option (FDv2 protocol)
• Connection mode switching for all FDv2 modes:
  • Streaming - real-time flag updates with polling fallback
  • Polling - periodic polling only
  • Offline - cached flags only, no network
  • One-Shot - initialize then stop (no persistent synchronizer)
  • Background - low-frequency polling for background state
  • Automatic - clear the override and use automatic mode selection
• Context identification
• Boolean flag evaluation

Quickstart

1. At the js-core repo root, install dependencies and build:

yarn && yarn build

2. Create an .env file in this directory (example-fdv2/) with your mobile key:

MOBILE_KEY=mob-your-mobile-key-here

3. Update the flag key in src/welcome.tsx if needed (defaults to sample-feature).

4. Run the app:

# iOS
yarn ios

# Android
yarn android

Note: You may need to run npx expo prebuild before the first iOS or Android build.

Caveats

• Network-based automatic mode switching is not yet implemented. The wiring is in place, but RNStateDetector does not yet emit network state changes. Lifecycle-based switching (foreground/background) works.
• The dataSystem option and setConnectionMode() are marked @internal and require @ts-ignore to use from TypeScript.