I was contacted and recruited for an initial phone screening. This screening consisted of resume questions and three multiple-choice iOS questions.

The next phase was an hour-long technical phone interview, which could be done in person or over the phone. I chose to do it over the phone.

I enjoyed talking to the Facebook engineer and thought it was a positive experience, even though I did not advance to the third leg of the interview process.

Given an array, remove the duplicates and return a unique array, keeping the first occurrence of the duplicates and the order.

Example: [@2, @1, @3, @1, @2] -> [@2, @1, @3]

How would you implement a call for canceling queued blocks with dispatch_after?