几种常见的GCD用法

GCD详细介绍 /**< 自定义queue，默认串行： NULL == DISPATCH_QUEUE_SERIAL*/ /**< label:标签，用于标注queue*/ // dispatch_queue_t queue = dispatch_queue_create("label", NULL); // // dispatch_async(queue, ^{ // NSLog(@"test"); // }); /**< 自定义queue，并行或串行： DISPATCH_QUEUE_CONCURRENT或DISPATCH_QUEUE_SERIAL*/ // dispatch_queue_t serial_queue = dispatch_queue_create("标签", DISPATCH_QUEUE_CONCURRENT); // dispatch_async(serial_queue, ^(){ // sleep(5); // NSLog(@"block_1"); // 尽管为异步调用且延迟3秒，但如果在serial队列中，block_1仍然先于block_2被打印出来 // }); // dispatch_async(serial_queue, ^(){ // NSLog(@"block_2"); // }); /**< 延迟执行*/ /**< (int64_t)(delayInSeconds * NSEC_PER_SEC)：转换成毫秒*/ // double delayInSeconds = 5.0; // dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC)); // dispatch_after(popTime, dispatch_get_main_queue(), ^(void){ // NSLog(@"5s delay"); // }); /**< 常用的异步并发执行*/ // dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT , 0), ^{ // sleep(5); // NSLog(@"block_1"); // }); // // dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT , 0), ^{ // NSLog(@"block_2"); // }); /**< 异步并回调主线程，常用ui更新*/ dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT , 0), ^{ dispatch_async(dispatch_get_main_queue(), ^{ NSLog(@"to do with ui"); }); });