I'm not a developer (or user) on iOS, but does it not have a similar design scheme for apps to Android (since ICS at least)? Would an app that looks like bootstrap fit in at all, and indeed would Apple even allow an app that resembles Bootstrap instead of its own design guidelines?
Bootstrap is totally configurable, we're just showing the default styling. In terms of Apple allowing alternate designs, I think they encourage it, just look at Garage Band ;-).
Of course, but if there was a standardised sort of style used by most applications, then recreating it using Bootstrap would seem like a lot of effort for little benefit. If there isn't much of a standard style, then this is really neat - that just seemed like an odd situation to me. My impression was that there would be a style, and Apple would enforce it, but it's great if that's not true. And fair enough, googling for Garage Band iPad..it looks unique.