dispatch_async on main_queue?

Question

I have seen this code snippet:

dispatch_async(dispatch_get_main_queue(), ^{     [self doSomeNetworkStuff]; }); 

This doesn't look like making much sense to me.

EDIT: To clarify the conditions of my question:

• The call to dispatch_async is performed from the main thread.
• The sent message doSomeNetworkStuff is the heavy lifting worker task.
• ... and is not only the UI-updating task.

Dispatch, sure, but using the main queue would just pull the dispatched task back to the ui thread and block it.

Please, am I missing something? Thanks.

Answer 1

dispatch_async lets your app run tasks on many queues, so you can increase performance. But everything that interacts with the UI must be run on the main thread. You can run other tasks that don't relate to the UI outside the main thread to increase performance.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{    //Add some method process in global queue - normal for data processing      dispatch_async(dispatch_get_main_queue(), ^(){     //Add method, task you want perform on mainQueue     //Control UIView, IBOutlet all here      });   //Add some method process in global queue - normal for data processing  });