React Native for Android: How we built the first cross-platform React Native app

This post details the development of the Ads Manager app, which was Facebook's first fully React Native app and the first cross-platform one. It covers the decision to use React Native for its potential upsides in code reuse (especially for complex business logic already in JavaScript) and faster development cycles. It describes the process of building the iOS version first, integrating existing Facebook libraries for authentication, analytics, crash reporting, networking, and push notifications, and the development of the Navigator component for complex navigation flows. It also details the challenges and solutions for building the Android version, emphasizing code reuse through platform-specific component abstractions and the complexities of managing separate iOS and Android code repositories, leading to a cron-job based sync strategy. The post highlights lessons learned regarding cross-repository development and the importance of testing on both platforms.