GCD定时器

//获得队列

dispatch_queue_t queue = dispatch_get_global_queue(0,0);

//创建一个定时器

self.time = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER,0,0, queue);

//设置开始时间

dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0* NSEC_PER_SEC));

//设置时间间隔

uint64_t interval = (uint64_t)(2.0* NSEC_PER_SEC);

//设置定时器

dispatch_source_set_timer(self.time, start, interval,0)

;//设置回调

dispatch_source_set_event_handler(self.time, ^{

//设置当执行五次是取消定时器

count++;if(count ==5){

dispatch_cancel(self.time);

}

});

//由于定时器默认是暂停的所以我们启动一下

//启动定时器

dispatch_resume(self.time);

//暂停

dispatch_suspend(self.timerG);

//播放

dispatch_resume(self.timerG);

//销毁

dispatch_source_cancel(self.timerG);