2014: Establishing our own mobile frameworks

Now, to celebrate the codebase’s 10-year anniversary, we’re shedding some light on the technical decisions behind this evolution, as well as their historical context. The app’s codebase reflects 10 years of evolution, spurred by technical decisions necessary to support the growing number of engineers working on the app, its stability, and, above all, the user experience. Without heavy caching from our build system, engineers would have to spend an entire workday waiting for the app to build.įBiOS was never intentionally architected this way.The app makes heavy use of code generation, spurred by Buck, our custom build system.There is almost zero raw usage of Apple’s SDK - everything has been wrapped or replaced by an in-house abstraction.It has dozens of dynamically loaded libraries (dylibs), and so many classes that they can’t be loaded into Xcode at once.

It’s full of C++, Objective-C(++), and Swift.

Since the app was rewritten in 2012, it has been worked on by thousands of engineers and shipped to billions of users, and it can support hundreds of engineers iterating on it at a time.Īfter years of iteration, the Facebook codebase does not resemble a typical iOS codebase: Facebook for iOS (FBiOS) is the oldest mobile codebase at Meta.

Install facebook app