GCD Timer

倒计时 定时器 timer

-(void)gcdTimeStartTime:(NSInteger)startTime withBlock:(void(^)(NSInteger time))currentTime {
    dispatch_queue_t queue = dispatch_get_main_queue();
    __block dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    __block NSInteger count  = startTime;
    dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
    dispatch_source_set_event_handler(timer, ^{
        count --;
        currentTime(count);
        if (count == 0) {
           dispatch_source_cancel(timer);
        }
    });
    dispatch_resume(timer);
    
}

循环执行定时器

@property (nonatomic ,strong) dispatch_source_t timer;//  注意:此处应该使用强引用 strong
-------------------------------------------------------------------------------
/**
 gcd 事件函数
 @param sleepTime 每多少秒发生一次
 @param currentTime 当前是第几次
 */
-(void)gcdEventTime:(NSInteger)sleepTime withBlock:(void(^)(NSInteger time))currentTime {
    
    if (self.timer) {
        return;
    }
    
    dispatch_queue_t queue = dispatch_get_main_queue();
    __block dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    __block NSInteger count  = 0;
    dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, sleepTime * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
    dispatch_source_set_event_handler(timer, ^{
        count ++;
        currentTime(count);
    });
    dispatch_resume(timer);
    self.timer = timer;

}
// 取消定时器
-(void)cancelTimer {
    if (self.timer) {
        dispatch_source_cancel(self.timer);
    }
}