IOS GCD Programming

Using GCD to handle multi-threading, under a multi-core CPU, will improve execution efficiency, and here is a section of the GCD code used in the project.

-(void) gcddownload  {      static dispatch_once_t once;      static dispatch_queue_t queue;      Create download Queue      dispatch_once (&once, ^{          queue =dispatch_queue_create (" Com.xxx.download.background ", dispatch_queue_concurrent);      });      __block type      __block BOOL downloadflag = NO;      Dispatch_async (queue, ^{  //        Downloadflag = [Download sendrequest:request];          NSLog (@ "Long-time tasks, such as network Downloads");      });        Dispatch_barrier_async (queue,^{          if (downloadflag) {              NSLog (@ "Download completed successfully");          }                    Dispatch_async (Dispatch_get_main_queue (), ^{              NSLog (@ "finished downloading, back to the main thread, such as Refresh UI");});    

　　

Multiple concurrent blocks can be placed in the queue.

IOS GCD Programming