Well this is one clue why - http://quellish.tumblr.com/post/126712999812/how-on-earth-the-facebook-ios-application-is-so http://quellish.tumblr.com/post/1267129

Well this is one clue why - http://quellish.tumblr.com/post/126712999812/how-on-earth-the-facebook-ios-application-is-so http://quellish.tumblr.com/post/126712999812/how-on-earth-th... Apparently (in 2015 at least), the iOS app had over 18,000 classes. There was even a presentation with a FB dev bragging about it's 'scale' tho suspiciously it's been scrubbed from the web