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.

Every now and then Apple release a new product, like TVOS for the Apple TV and people ask why Apple wrote an entirely new OS. why not base it on iOS or OSX. of course that's exactly what they do. There's a common core to OSX, iOS and now TVOS that are almost entirely the same code base. Which specific files are common or different for each flavour probably changes from time to time and this may well be a case of that.

The fact is though, iOS and OSX are already as much the same code base as they can be, and as much different as they need to be. That balance may change as the OSes evolve, but I don't think there's any pressing need or benefit to converging them completely.

In and of itself that doesn't prove anything. That file has had symbols for multiple architectures since forever, including CPUs like M68K, Sparc (years ago, I had hoped that Apple would buy Sun instead of Oracle - oh well) and VAX (but not Alpha).

https://github.com/opensource-apple/xnu/blob/10.11/osfmk/mac...

No.

https://news.ycombinator.com/item?id=12772801