Yeah, I know, it's a somewhat complicated story. But even the kernel has, as the Wikipedia article confirms, considerable BSD heritage, and the userland is even more BSD flavored. I would think that the vast majority of Mac / iOS programmers has never made a direct Mach system call in their code.
At the very least, you can say that OS X is more BSD than Linux is GNU.
The vast majority also doesn't do POSIX stuff, rather Objective-C and Swift framework calls.
The UNIX compatibility on NeXTSTEP, and follow up culture on OS X, was that BSD layer was to bring UNIX stuff into the system and get those DoD contracts, not much so for the software born on the platform.
At the very least, you can say that OS X is more BSD than Linux is GNU.