I don't believe Apple has embraced Rust the same way Google has. Particularly their firmware is still very based on C.
https://discourse.llvm.org/t/rfc-enforcing-bounds-safety-in-...
> I've mostly given up on the standard C library. Many of its facilities, particularly stdio, seem designed to encourage bugs. A big chunk of qmail is stolen from a basic C library that I've been developing for several years for a variety of applications. The stralloc concept and getln() make it very easy to avoid buffer overruns, memory leaks, and artificial line length limits.