If you know how to program with or Cocoa Cocoa Touch, this guide will help you get started with immediately GCD, with many examples to help you write high-performance multithreaded applications. Pack your code as an object block and call them with GCD Understanding queue delivery? In the thread pool managed by the GCD Use different methods to implement the UI and non-UI tasks Create a task group that can be run at once Instruct GCD GCD to carry out the task only once or after a delay Discover how to build your own dispatch queue