- (void)delay1{ // 延迟执行不要用sleep，坏处：卡住当前线程 [NSThread sleepForTimeInterval:3]; NSLog(@"操作");}- (void)delay2{ // 一旦定制好延迟任务后，不会卡主当前线程}- (void)delay3{ // 3秒后回到主线程执行block中的代码 dispatch_queue_t queue = dispatch_get_main_queue(); dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), queue, ^{ NSLog(@"------task------%@", [NSThread currentThread]); });}- (void)delay4{ // 3秒后自动开启新线程 执行block中的代码 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), queue, ^{ NSLog(@"------task------%@", [NSThread currentThread]); });}原文：http://www.cnblogs.com/vshiron/p/5043417.html