OC 线程操作

- (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];
//　　 [self syncMain];//主线程操作直接死锁

　　　　[NSThread detachNewThreadSelector:@selector(syncMain) toTarget:self withObject:nil];//在子线程地调用，会直接执行，不会死锁

  
}


/**
 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]);
    });
}

　　

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