OC 线程操作 - GCD使用 -同步函数，异步函数，串行队列，并发队列

 

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- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{       //    GCD 开几条线程并不是我们可以控制的，而是系统来决定的，       //    [self asyncConcurrent]; //    [self asyncSerial]; //    [self syncConcurrent]; //    [self syncSerial]; //    [self test_get_global_queue];<br>//　　 [self syncMain];//主线程操作直接死锁<br><br>　　　　[NSThread detachNewThreadSelector:@selector(syncMain) toTarget:self withObject:nil];//在子线程地调用，会直接执行，不会死锁<em id="__mceDel">  }     /**  异步函数 + 并发队列  ：会开启多条线程，队列中的任务是异步执行的（并发执行）(无序执行的)  */ - (void)asyncConcurrent{           //1.创建任务     /*      参数1：const char * _Nullable label  ， C语言参数 字符串 ，标识符，为了区分队列的 推荐写法：反着写      参数2：dispatch_queue_attr_t  _Nullable attr，队列类型      DISPATCH_QUEUE_CONCURRENT 并发，      DISPATCH_QUEUE_SERIAL 串行      */     dispatch_queue_t queue = dispatch_queue_create("com.520it.www", DISPATCH_QUEUE_CONCURRENT);           //2  2.1封装任务 2.2添加到任务队列中     /**      dispatch_async(<#dispatch_queue_t  _Nonnull queue#>, <#^(void)block#>)      参数1：dispatch_queue_t  _Nonnull queue 队列      参数2：<#^(void)block#>  要执行的任务      */     dispatch_async(queue, ^{         NSLog(@"打印一下111 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下222 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下333 --- %@", [NSThread currentThread]);     }); }     /**  异步函数 + 串行队列：可以开启线程，但是串行队列只会在同一个子线程执行  */ - (void)asyncSerial{     dispatch_queue_t queue = dispatch_queue_create("asyncSerial", DISPATCH_QUEUE_SERIAL);     dispatch_async(queue, ^{         NSLog(@"打印一下111 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下222 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下333 --- %@", [NSThread currentThread]);     }); }     /**  同步函数 + 并发队列  ：不会会开启多条线程，不管后面是并发还是串行，任务是串行执行的  */ - (void)syncConcurrent{           //1.创建任务       dispatch_queue_t queue = dispatch_queue_create("com.520it.www", DISPATCH_QUEUE_CONCURRENT);       dispatch_sync(queue, ^{         NSLog(@"打印一下111 --- %@", [NSThread currentThread]);     });           dispatch_sync(queue, ^{         NSLog(@"打印一下222 --- %@", [NSThread currentThread]);     });           dispatch_sync(queue, ^{         NSLog(@"打印一下333 --- %@", [NSThread currentThread]);     }); }   /**  同步函数 + 串行队列  ：不会会开启多条线程，不管后面是并发还是串行，任务是串行执行的  */ - (void)syncSerial{     dispatch_queue_t queue = dispatch_queue_create("syncSerial", DISPATCH_QUEUE_SERIAL);     dispatch_sync(queue, ^{         NSLog(@"打印一下111 --- %@", [NSThread currentThread]);     });           dispatch_sync(queue, ^{         NSLog(@"打印一下222 --- %@", [NSThread currentThread]);     });           dispatch_sync(queue, ^{         NSLog(@"打印一下333 --- %@", [NSThread currentThread]);     }); }       /**  获得全局队列  */ -(void)test_get_global_queue{           /**      获得全局并发队列 ： 这个队列已经存在的， 我们只是获得      参数1 ： long identifier 优先级，       DISPATCH_QUEUE_PRIORITY_HIGH 2       DISPATCH_QUEUE_PRIORITY_DEFAULT 0       DISPATCH_QUEUE_PRIORITY_LOW (-2)       DISPATCH_QUEUE_PRIORITY_BACKGROUND INT16_MIN    这是最低的优先级             参数2 ： unsigned long flags 给未来使用， 总是给个0      */     dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);     dispatch_async(queue, ^{         NSLog(@"打印一下111 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下222 --- %@", [NSThread currentThread]);     });           dispatch_async(queue, ^{         NSLog(@"打印一下333 --- %@", [NSThread currentThread]);     }); } </em>

　　

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