That turned out not to be quite as true as they said it was...
> While the WWDC app does in fact use Swift, it’s not as much as you might think. Out of 281 classes, only 6 are written in Swift. The Apple Store app is also using Swift for its watch app. That’s about all the production Swift I could find from Apple on iOS.
Federighi said on Gruber's podcast that the Dock team completely rewrote Dock in Swift. However most of the other OS X teams are only testing the waters. A big part of it is lack of 32-bit support for Swift apps.
" the team that does the Dock and the window management on OS X, implemented all their new features for El Capitan in Swift and started mass-converting all of their code, and say that they couldn’t imagine going back and that they’re more productive with it."
> While the WWDC app does in fact use Swift, it’s not as much as you might think. Out of 281 classes, only 6 are written in Swift. The Apple Store app is also using Swift for its watch app. That’s about all the production Swift I could find from Apple on iOS.
Source: https://medium.com/@ryanolsonk/is-apple-using-swift-4a6c80f7...