Earlier quoted context omitted.
Don't iPhones and iPads also have a UNIX kernel?
It's complicated. Original UNIX by AT&T was newer open-sourced. BSD (Berkley Software Distribution) was opensource distribution of user programs for UNIX (like TCP/IP stack, vi editor, etc.), used by original UNIX, with proportions 20% of AT&T code and 80% of BSD code. So technically, BSD is(0.8) not(0.2) UNIX. FreeBSD is branched from BSD code, so it is(0.8) not(0.2) UNIX too. Apple MacOS X is based on FreeBSD code…
The system as a whole is able to brand itself as UNIX compliant, though, because it complies with the Single UNIX Specification. That spec is concerned about userspace behavior, not kernel or implementation, and you don't have to include any actual UNIX source code to be able to brand your OS as a "UNIX" according to the spec and trademark guidelines.