《iOS多线程简介》中提到:GCD中有2个核心概念:1、任务(执行什么操作)2、队列(用来存放任务)
那么多线程GCD的基本使用有哪些呢?
可以分以下多种情况:
1、异步函数 + 并发队列
/** * 异步函数 + 并发队列:可以同时开启多条线程 */- (void)asyncConcurrent{ // 1.创建一个并发队列 // dispatch_queue_create(const char *label, dispatch_queue_attr_t attr); // label : 相当于队列的名字 // dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_CONCURRENT); // 1.获得全局的并发队列 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); // 2.将任务加入队列 dispatch_async(queue, ^{ for (NSInteger i = 0; i<3; i++) { NSLog(@"this is first %@",[NSThread currentThread]); } }); dispatch_async(queue, ^{ for (NSInteger i = 0; i<3; i++) { NSLog(@"this is second %@",[NSThread currentThread]); } }); dispatch_async(queue, ^{ for (NSInteger i = 0; i<3; i++) { NSLog(@"this is third %@",[NSThread currentThread]); } }); }
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2、同步函数 + 并发队列
/** * 同步函数 + 并发队列:不会开启新的线程 */- (void)syncConcurrent{ // 1.获得全局的并发队列 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); // 2.将任务加入队列 dispatch_sync(queue, ^{ NSLog(@"this is first %@",[NSThread currentThread]); }); dispatch_sync(queue, ^{ NSLog(@"this is second %@",[NSThread currentThread]); }); dispatch_sync(queue, ^{ NSLog(@"this is third %@",[NSThread currentThread]); }); }
3、异步函数 + 串行队列
/** * 异步函数 + 串行队列:会开启新的线程,但是任务是串行的,执行完一个任务,再执行下一个任务 */- (void)asyncSerial{ // 1.创建串行队列 dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL); // dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", NULL); // 2.将任务加入队列 dispatch_async(queue, ^{ NSLog(@"this is first %@",[NSThread currentThread]); }); dispatch_async(queue, ^{ NSLog(@"this is second %@",[NSThread currentThread]); }); dispatch_async(queue, ^{ NSLog(@"this is third %@",[NSThread currentThread]); });}
4、同步函数 + 串行队列
/** * 同步函数 + 串行队列:不会开启新的线程,在当前线程执行任务。任务是串行的,执行完一个任务,再执行下一个任务 */- (void)syncSerial{ // 1.创建串行队列 dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL); // 2.将任务加入队列 dispatch_sync(queue, ^{ NSLog(@"this is first %@",[NSThread currentThread]); }); dispatch_sync(queue, ^{ NSLog(@"this is second %@",[NSThread currentThread]); }); dispatch_sync(queue, ^{ NSLog(@"this is third %@",[NSThread currentThread]); });}
5、异步函数 + 主队列
// * 异步函数 + 主队列:只在主线程中执行任务- (void)asyncMain{ // 1.获得主队列 dispatch_queue_t queue = dispatch_get_main_queue(); // 2.将任务加入队列 dispatch_async(queue, ^{ NSLog(@"this is first %@",[NSThread currentThread]); NSLog(@"this is second %@",[NSThread currentThread]); NSLog(@"this is third %@",[NSThread currentThread]); });}
6、同步函数 + 主队列
// * 同步函数 + 主队列:- (void)syncMain{ NSLog(@"begin"); // 1.获得主队列 dispatch_queue_t queue = dispatch_get_main_queue(); // 2.将任务加入队列 dispatch_sync(queue, ^{ NSLog(@"this is %@",[NSThread currentThread]); }); NSLog(@"end");}
造成“相互等待的死锁”
原标题:iOS 多线程GCD的基本使用
关键词:IOS