GCD understanding 1 (synchronous-asynchronous, serial-parallel), gcd asynchronous

GCD understanding 1 (synchronous-asynchronous, serial-parallel), gcd asynchronous

1. Parallel-asynchronous (ST1 and ST2 seize resources)

1-1) obtain the parallel (global) queue. The default priority is DISPATCH_QUEUE_PRIORITY_DEFAULT.

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT , 0);

1-2) create an asynchronous event.

dispatch_async(queue, ^{//do something 1   });dispatch_async(queue, ^{//do something 2   });

 

2. Serial-synchronization (sequential execution)

2-1) create a serial queue, and DISPATCH_QUEUE_SERIAL is a serial

dispatch_queue_t queue =  dispatch_queue_create("test", DISPATCH_QUEUE_SERIAL);

2-2) create a synchronization event.

dispatch_sync(queue, ^{//do something 1    });dispatch_sync(queue, ^{//do something 2   });

 

3. Parallel-synchronization (sequential execution)

3-1) obtain the parallel (global) queue. The default priority is DISPATCH_QUEUE_PRIORITY_DEFAULT.

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT , 0);

3-2) create a synchronization event.

dispatch_sync(queue, ^{//do something 1    });dispatch_sync(queue, ^{//do something 2   });

 

4. Serial-asynchronous (strange to understand, test results, and sequential execution)

4-1) create a serial queue, and DISPATCH_QUEUE_SERIAL is a serial

dispatch_queue_t queue =  dispatch_queue_create("test", DISPATCH_QUEUE_SERIAL);

4-2) create an asynchronous event.

dispatch_async(queue, ^{//do something 1    });dispatch_async(queue, ^{//do something 2   });

 

Generally, 1-3 is enough, right ?!