队列queue.h方法总览

queue.h

创建队列（queue）相关方法：

/**
 获取当前队列 macos(10.6,10.9), ios(4.0,6.0))
 */
dispatch_queue_t
dispatch_get_current_queue(void);

/**
 获取主队列（串行）macos(10.6), ios(4.0)
 */
dispatch_queue_t
dispatch_get_main_queue(void)；

/**
 全局队列 ：本质就是并发队列；不可跟踪；在MRC中释放次数不一样  macos(10.6), ios(4.0)

 @param identifier  优先级
                    #define DISPATCH_QUEUE_PRIORITY_HIGH 2
                    #define DISPATCH_QUEUE_PRIORITY_DEFAULT 0
                    #define DISPATCH_QUEUE_PRIORITY_LOW (-2)
                    #define DISPATCH_QUEUE_PRIORITY_BACKGROUND INT16_MIN
 @param flags 预留（无用）一般为0
 */
dispatch_queue_t
dispatch_get_global_queue(long identifier, unsigned long flags);

/**
 根据已知队列创建队列 macos(10.12), ios(10.0), tvos(10.0), watchos(3.0)

 @param label 标签 eg: @"com.Maker"
 @param attr 属性（attribute）可以通过dipatch_queue_attr_make_with_qos_class或
dispatch_set_target_queue方法设置 dispatch_queue_attr_t
 @param target 目标队列，相当于目标队列计数 加一
 */
dispatch_queue_t
dispatch_queue_create_with_target(const char *_Nullable label,
    dispatch_queue_attr_t _Nullable attr, dispatch_queue_t _Nullable target)
    DISPATCH_ALIAS_V2(dispatch_queue_create_with_target);

/**
 创建队列（串行 / 并发） macos(10.6), ios(4.0)

 @param label 标签 eg: @"com.Maker"
 @param attr 属性（attribute）可以通过dipatch_queue_attr_make_with_qos_class或
dispatch_set_target_queue方法设置 dispatch_queue_attr_t
 */
dispatch_queue_t
dispatch_queue_create(const char *_Nullable label,
        dispatch_queue_attr_t _Nullable attr);

举例说明：

//当前队列
dispatch_queue_t currentQueue = dispatch_get_current_queue();
dispatch_async(currentQueue, ^(){
    for (int i = 0; i < 100; i++) {
        NSLog(@"任务_1====%d",[NSThread currentThread].isMainThread);
    }
});

//主队列
dispatch_queue_t mainQueue = dispatch_get_main_queue();
dispatch_async(mainQueue, ^(){
    for (int i = 0; i < 100; i++) {
        NSLog(@"任务_1====%d",[NSThread currentThread].isMainThread);
    }
});

//全局队列
dispatch_queue_t globalQueue = dispatch_get_global_queue(0, 0);
dispatch_async(globalQueue, ^(){
    for (int i = 0; i < 100; i++) {
        NSLog(@"任务_1====%d",[NSThread currentThread].isMainThread);
    }
});

//target队列
dispatch_queue_attr_t attr = dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_CONCURRENT, QOS_CLASS_BACKGROUND, -1);
dispatch_queue_t queue = dispatch_queue_create("com.Maker", attr);
dispatch_queue_t targetQueue = dispatch_queue_create_with_target("com.Maker", attr, queue);
dispatch_async(targetQueue, ^(){
    for (int i = 0; i < 10; i++) {
        NSLog(@"任务_1====%d",[NSThread currentThread].isMainThread);
    }
});
dispatch_async(targetQueue, ^(){
    for (int i = 0; i < 10; i++) {
        NSLog(@"任务_2====%d",[NSThread currentThread].isMainThread);
    }
});

//创建队列
dispatch_queue_attr_t attr = dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_SERIAL, QOS_CLASS_UTILITY, -1);
dispatch_queue_t globalQueue = dispatch_queue_create("com.Maker", attr);
dispatch_async(globalQueue, ^(){
    for (int i = 0; i < 100; i++) {
        NSLog(@"任务_1====%d",[NSThread currentThread].isMainThread);
    }
});