A bit useless. Are they using it in the top ten (mail, web, cal, clock, etc.)? How much of Swift compared to ObjC code? Those are the real answers I would expect to read in your article.
>Are they using it in the top ten (mail, web, cal, clock, etc.)?
No.
>How much of Swift compared to ObjC code?
Much less.
It makes sense too. You don't rewrite perfectly good programs in a new language just for the fun of it.
The Holy Grail of software engineering
It also allowed us to get more people involved in development. People new to apple development found Objective-C to be a bigger barrier. Odd syntax and a bit old fashion.
Mind you I quite liked Objective-C. But it seems a bit pointless when you got Swift.