首先 宏定义

static dispatch_source_t _sourceTimer;  

 然後zai需要的地方設置

  //创建全局队列
                dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
                
                //使用全局队列创建计时器
                _sourceTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
                
                //定时器延迟时间
                NSTimeInterval delayTime = 1.0f;
                
                //定时器间隔时间
                NSTimeInterval timeInterval = 100.0f;
                
                //设置开始时间
                dispatch_time_t startDelayTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayTime * NSEC_PER_SEC));
                
                //设置计时器
                dispatch_source_set_timer(_sourceTimer,startDelayTime,timeInterval*NSEC_PER_SEC,NSEC_PER_SEC);
                
                //执行事件
                dispatch_source_set_event_handler(_sour