At the heart of Uber’s mobile app development are four primary apps: Android rider, Android driver, iOS rider, and iOS driver. Android developers build in Java, iOS in Objective C and Swift. Engineers across both platforms land code into a monolithic code base that ships each week.
They use some third-party libraries, but often build their own, since “Many open source libraries available are general-purpose, which can create binary bloat. For mobile engineering, every kilobyte matters.”
On Android, the build system is Gradle. For the UI, Butter Knife binds views and callbacks to fields and methods via annotation processing, and Picasso provides image loading.
As for iOS, all of the code lives in a monorepo built with Buck. For crash detection, KSCrash reports crashes to the internal reporting framework.