[woodruffw]

I think that source is a little bit confused on the distinction between iOS and OS X (macOS?).

iOS and OS X share the same kernel, named XNU (it's the userlands of the two that are almost completely different). That's been the case since iOS 1. Whenever either OS X or iOS gets ported to a new CPU (or CPU subfamily), the kernel gets another set of macros added to it for the purpose of identifying the new CPU. The presence of a new ARM macro in XNU doesn't mean much at all - it already has a ton of them, as well as truly ancient macros from long-forgotten systems (m68/88k comes to mind). Those macros have nothing to do with OS X or iOS individually - they're relevant primarily to the kernel itself.