Dispatch_async Child threads, simple usage of the main thread

How to use child threads:

0), ^{     // child thread processing logic   });

Dispatch_queue_priority_default the priority of the team column, which contains the following parameters

Dispatch_queue_priority_high,

Dispatch_queue_priority_low,

　Dispatch_queue_priority_background

0 is a reserved value, temporarily without any effect, the default pass a 0 can be

How to use the main thread:

Dispatch_async (Dispatch_get_main_queue (), ^{     ///main thread processing logic });

If the child threads also need to update some UI and other operations, this time need to be in the main thread inside to complete, that is, the child thread inside can be nested the main thread, the specific use of the following methods:

0), ^{     // child thread processing logic                     ^        {/ / The main thread updates the UI and the like     );               });

Dispatch_async Child threads, simple usage of the main thread