dispatch_async(dispatch_get_global_queue(0, 0), ^{     //后台程执行 something; }); 

dispatch_async(dispatch_get_main_queue(), ^{    // 主线程执行something;});

static dispatch_once_t onceToken;dispatch_once(&onceToken, ^{     // 主要用于单例});

double delayInSeconds = 2.0;dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PE R_SEC);dispatch_after(popTime, dispatch_get_main_queue(), ^(void){     // code to be executed on the main queue after delay});

dispatch_queue_t myQueue = dispatch_queue_create("com.cnblogs.yybz", NULL); dispatch_async(myQueue, ^{    // your code});

dispatch_queue_t myQueue = dispatch_queue_create("com.cnblogs.yybz", NULL); dispatch_queue_t globalHightQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0); dispatch_set_target_queue(myQueue, globalHighQueue);

dispatch_group_async(group, queue, ^{     // code}); dispatch_group_wait(group, DISPATCH_TIME_FOREVER); //超时参数 dispatch_group_notify(group, queue, ^{    // code});dispatch_group_enter(group);dispatch_async(queue, ^{    //code    dispatch_group_leave(group);});

/**@parameter iterations 迭代器数量@parameter queue 提交任务的队列@parameter (^block)(size_t) 任务Block,size_t 为迭代器下标**/dispatch_apply(size_t iterations, dispatch_queue_t queue, void (^block)(size_t));

dispatch_suspend(queue); dispatch_resume(myQueue);

dispatch_semaphore_create; //创建一个semaphoredispatch_semaphore_signal; //发送一个信号dispatch_semaphore_wait; //等待信号