时间倒计时

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:@selector(timerFire:) userInfo:nil repeats:YES];

}

//////每隔一秒执行一次

- (void)timerFire:(NSTimer *)timer

{

NSCalendar *calendar = [NSCalendar currentCalendar];

NSDateComponents *components = [[NSDateComponents alloc] init];

[components setYear:2016];

[components setMonth:12];

[components setDay:12];

[components setHour:12];

[components setMinute:0];

[components setSecond:0];

[components setNanosecond:0];

NSDate *fireDate = [calendar dateFromComponents:components];//目标时间

NSDate *today = [NSDate date];//当前时间

unsigned int unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond| NSCalendarUnitNanosecond;

NSDateComponents *d = [calendar components:unitFlags fromDate:today toDate:fireDate options:0];//计算时间差

NSLog(@"%@",[NSString stringWithFormat:@"%d天%d小时%d分%d秒%d毫秒", [d day], [d hour], [d minute], [d second],[d nanosecond]/10000000]);

//    auctionTime.text = [NSString stringWithFormat:@"%d天%d小时%d%分%d秒", [d day], [d hour], [d minute], [d second]];//倒计时显示