GCD for 循环延迟执行

0.05 为延迟时间,可调

dispatch_queue_t serialQueue = dispatch_queue_create("serialQueue", DISPATCH_QUEUE_SERIAL);

dispatch_async(serialQueue, ^{

            dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);

             for (i=0 ; i<100; i++) {

                     dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.05 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

                                //在这里执行相关代码

                                NSLog(@"当前i  ==== %d",i);                        

                              dispatch_semaphore_signal(semaphore);

                     });

                dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);

        }

});