> I suppose I could modify my argument to start talking about iOS, which is based on FreeBSD but closed, in comparison to Android.
Sorry, iOS and OS X are the same operating system, so you really could not :-). iOS and OS X have slightly different but very similar closed source Cocoa layers.
I don't want to split hairs about what "the same operating system" means so I'll just point out that the xnu source code doesn't include any iOS code AFAIK.
"Sorry", but a lot of the code that is specific to iOS is in the kernel, and almost none of it is open source; claiming that the iOS kernel is open source is simply preposterous. The situation is even worse if you start looking at drivers, none of which are open source on that platform; but even the core kernel is missing major pieces on ARM.
Yup. Both use Foundation, but Cocoa (OS X) uses Application Kit and Cocoa Touch (iOS) uses UIKit. Foundation itself is based largely on OpenStep, of which there are several opensource variants you can check out.
Sorry, iOS and OS X are the same operating system, so you really could not :-). iOS and OS X have slightly different but very similar closed source Cocoa layers.