First of all I mentioned most, not all.

Second, while OS X, and NeXTSTEP before it, are technically UNIX, they aren't seen as such by either NeXT, nor Apple.

The focus of the whole userspace experience is on Objective-C frameworks, nowadays also a mix of Swift and C++.

Steve Jobs was famously against UNIX culture, there was even a famous attendance of him at USENIX.

NeXTSTEP was based on UNIX, because Steve Job wanted to win the workstation market against Sun, using UNIX compatibility as EEE, bringing folks into NeXTSTEP and keeping them there with Objective-C development experience, Lotus Improv, Renderman and such.

> NeXTSTEP was based on UNIX, because Steve Job wanted to win the workstation market against Sun, using UNIX compatibility as EEE, bringing folks into NeXTSTEP and keeping them there with Objective-C development experience, Lotus Improv, Renderman and such.

So Embrace, Extend and Extinguish?

If macOS isn't see as UNIX by Apple, why does the latter continue to submit it for certification?

Is the OSX kernel not written in C?

the modular parts (IOKit) are C++