5Star Interview Question on iOS Concurrency : NSOperation and Dispatch Queues Concurrency is always considered a monster of a subject in iOS development. It can be considered a dangerous area that many developers try their best to avoid. Rumor has it that multithreaded code should be avoided as much as you can. I agree with you that concurrency can be dangerous so if you don’t understand it very well. It is only dangerous because of the unknown. Think of how many dangerous actions or activities that people do in their life, many right? But once they master it, it becomes a piece of cake. Concurrency is a two sided-weapon that you should master and learn how to use it. It helps you to write efficient, fast execution, and responsive apps, but at the same time, misusing it will ruin your app with no mercy. That’s why before starting writing any concurrency code, think first why do you need concurrency and which API do you need to use to solve this problem? In iOS we ha...