Not necessarily on topic - but given your code samples are written in Objective-C, how much of your codebase is still in Objective-C and what's your opinion on porting it over to Swift?
Good q. All of it is still Objective C and C++; there's a few blockers to starting to move to Swift, including the relatively large amount of custom build + development tooling that we and FB have in place.
It's getting used more and more in our app--few recent examples are the "Promote Post" UI if you're a business account and want to promote a post from inside Instagram, the Saved Posts feature, and the comment moderation tools we now provide around comment filtering.
Peculiar this is being downvoted - compiler speed / reliability / support for incremental builds are all issues with large Swift projects. I've even see people go as far as splitting up their project into frameworks in order to bring build times below times as large as 10m and restore incremental compilation.