Apple Software Developer interview questions

This was a phone interview. The interviewer called me on time, and we started our discussion. The interviewer was very professional. We chatted on what I did in my current company, and then spend the rest of the hour on the following question.

Phone screen, then 3 hours of onsite interviews. Asynchronous programming and logic questions. System design. Questions were difficult but interesting. Typical from any major software company, eg similar to Amazon. Didn't ask behavioral questions, just technical.