강경하다

GCD (Grand Central Patch) : GCCD procides and manages FIFO queues to which your application can submit tasks in the form of block objects. Work submitted to dispatch queues are executed on a pool of threads fully managed by the system. No guarantee is made as to the thread on which a task executes. - Apple document => 해야 할 일들(코드블럭)을 GCD에 넘기면, 시스템이 알아서 쓰레드를 할당하여 안전하게 처리해준다. Dispatch queue 에는 3가지 ..