Grand Central Dispatch is one of the greatest (grandest even?) ways to do multithreaded applications in any language, which if you’re doing any kind of processing or network communication, it’s likely you will need to make your application use multiple threads too. In this episode we take a look at the main use cases for GCD and the simple code you need to write to run certain tasks in another thread by using queues and blocks.

https://motioninmotion.tv/screencasts/15