I applied for an iOS position and was initially contacted via LinkedIn. Overall, I really enjoyed the process, though it was quite drawn out due to personal circumstances.

I interviewed from Australia. The initial stage involved a phone screening interview with five fairly basic iOS questions, focusing on understanding blocks and ARC. This was followed by two technical phone interviews that included algorithmic coding questions, verbal discussions about my past work experience, and further technical iOS questions.

After passing these two phone interviews, I was flown out to Menlo Park for a day of interviews. There were five interviews in total:

• An initial chat to warm up, discussing past experience, working relationships, etc., and a brief coding question on a whiteboard.
• Three more technical interviews, similar in format to the initial phone interviews.
• One interview focused on designing scalable iOS app architecture for a simple app.

I really enjoyed the process and found the recruiters very helpful and friendly. Visiting Facebook HQ was great, and as the reviews suggest, all the people were great. I recommend it for the experience.

Getting an offer is tough. For me, it came down to not being quick enough in answering questions during the onsite technical interviews. The questions weren't overly difficult, but they expect you to move fast. I tended to take my time and discuss with the interviewers, which I believe worked against me. Another aspect was a general lack of experience (I have 18 months of experience), which was reflected particularly in the iOS design interview.

I hope this helps others considering going through the process. I definitely recommend it!

An interesting, exhaustive phone number pad permutations question. For example, if you touch one number on a keypad and then drag it around the keypad (horizontal and vertical movements only, no repeats), enumerate all the possible words you could create. These sorts of questions are common.

Implement an LRU cache. Make it thread-safe.