IOS GCD (Serial, concurrent basic use of threads)

General function names with Create\copy\new\retain and other words, need to use this data when the release// GCD data type in the ARC environment does not need to do release// The data type of the CF (Core Foundation) still needs to be release in the ARC environment    

@implementationHmviewcontroller- (void) viewdidload{[Super Viewdidload];    [Self performselectorinbackground: @selector (Test) Withobject:nil]; //[self syncmainqueue];}- (void) test{NSLog (@"Test---%@", [Nsthread CurrentThread]); Dispatch_async (Dispatch_get_global_queue (Dispatch_queue_priority_default,0), ^{NSLog (@"Task---%@", [Nsthread CurrentThread]); });} /** * Use Dispatch_async async functions to add tasks to the main queue    in the main thread */-(void ) Asyncmainqueue {    //1. Get the home rowdispatch_queue_t queue =Dispatch_get_main_queue (); //2. Add a task to the queue to executeDispatch_async (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]); });} /** * Use the Dispatch_sync synchronization function to add a task to the primary queue in the main thread: The task cannot be executed down  /-(void  ) Syncmainqueue {    //1. Get the home rowdispatch_queue_t queue =Dispatch_get_main_queue (); //2. Add a task to the queue to executeDispatch_sync (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]); });//dispatch_sync (queue, ^{//NSLog (@ "----Download Picture 2-----%@", [Nsthread CurrentThread]);//    });//dispatch_sync (queue, ^{//NSLog (@ "----Download Picture 3-----%@", [Nsthread CurrentThread]);//    }); //does not open a new thread, all tasks are executed in the main thread}//all functions, such as create\copy\new\retain, need to be release when the data is not needed.//GCD data types do not need to be release in the ARC environment//The data type of the CF (Core Foundation) still needs to be release in the ARC environment /** * Use Dispatch_sync sync function to add a task to the string  /-(void  ) Syncserialqueue {    //1. Create a serial queuedispatch_queue_t queue = Dispatch_queue_create ("Com.itheima.queue", NULL); //2. Add a task to the queue to executeDispatch_sync (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]);    }); Dispatch_sync (Queue,^{NSLog (@"----Download Image 2-----%@", [Nsthread CurrentThread]);    }); Dispatch_sync (Queue,^{NSLog (@"----Download Image 3-----%@", [Nsthread CurrentThread]);        }); //3. Releasing Resources//dispatch_release (queue); //MRC (non-ARC)//Summary: New threads are not opened} /** * Use Dispatch_sync synchronization function to add tasks to the concurrent queue  */-(void  ) Syncglobalqueue {     //  1. Get the global concurrent queue dispatch_queue_t queue = Dispatch_get_global_queue (dispatch_queue_priority_        DEFAULT, 0); //2. Add a task to the queue to executeDispatch_sync (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]);    }); Dispatch_sync (Queue,^{NSLog (@"----Download Image 2-----%@", [Nsthread CurrentThread]);    }); Dispatch_sync (Queue,^{NSLog (@"----Download Image 3-----%@", [Nsthread CurrentThread]);        }); //Summary: New threads are not opened and concurrent queues lose concurrency} /** * Add tasks to the serial queue with the Dispatch_async async function  */-(void  ) Asyncserialqueue {     //  1. Create serial queue dispatch_queue_t queue = dispatch_queue_create ("com.itheima.queue         ", NULL); //2. Add a task to the queue to executeDispatch_async (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]);    }); Dispatch_async (Queue,^{NSLog (@"----Download Image 2-----%@", [Nsthread CurrentThread]);    }); Dispatch_async (Queue,^{NSLog (@"----Download Image 3-----%@", [Nsthread CurrentThread]);        }); //Summary: Execute a task with only 1 threads open} /** * Add task to concurrent queue with Dispatch_async async function  */-(void  ) Asyncglobalqueue {     //  1. Get the global concurrent queue dispatch_queue_t queue = Dispatch_get_global_queue (dispatch_queue_priority_        DEFAULT, 0); //2. Add a task to the queue to executeDispatch_async (Queue, ^{NSLog (@"----Download Image 1-----%@", [Nsthread CurrentThread]);    }); Dispatch_async (Queue,^{NSLog (@"----Download Image 2-----%@", [Nsthread CurrentThread]);    }); Dispatch_async (Queue,^{NSLog (@"----Download Image 3-----%@", [Nsthread CurrentThread]);        }); //Summary: 3 threads Open at the same time}@end

IOS GCD (Serial, concurrent basic use of threads)