No code reviews. One single developer owns a lot of code. Extremely tied deadlines with very high expectations. Things get pushed out all the time. No real team work. Just code in time, send it to QA, they'll find 10000 bugs... problem, you only have a week to fix everything. Guess what, *hit gets pushed out.

In other words, there's no time to right quality code at Apple. Either you're an extremely talented and organized developer, or, you'll keep shipping ugly code.