iOS NSTimer 实现倒计时

最新推荐文章于 2022-05-14 22:04:14 发布

转载最新推荐文章于 2022-05-14 22:04:14 发布 · 780 阅读

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本文介绍了如何从CocoaChina上获取NSTimer与日期操作的结合应用实例，包括定时器的配置、日期组件的使用及日期时间格式转换，通过实例演示了如何实现倒计时功能，并在不同场景下进行时间差计算，最终将结果显示为用户可读的时间格式。

从cocoachina上demo 获取

[NSTimer
 scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerFireMethod:) userInfo:nil repeats:YES];

  

//

-
 (void)timerFireMethod:(NSTimer
 *)theTimer 

{

    BOOL

timeStart = YES; 

    NSCalendar
 *cal = [NSCalendar currentCalendar];//定义一个NSCalendar对象

    NSDateComponents
 *endTime = [[NSDateComponents alloc] init];    //初始化目标时间...

    NSDate
 *today = [NSDate date];    //得到当前时间

      

    NSDateFormatter
 *dateFormatter = [[NSDateFormatter alloc] init]; 

    [dateFormatter
 setDateFormat:@"yyyy-MM-dd
 HH:mm:ss"];

    NSDate
 *dateString = [dateFormatter dateFromString:todate]; 

    NSString
 *overdate = [dateFormatter stringFromDate:dateString]; 

//   
 NSLog(@"overdate=%@",overdate); 

    static

int 
year; 

    static

int 
month; 

    static

int 
day; 

    static

int 
hour; 

    static

int 
minute; 

    static

int 
second; 

    if(timeStart)
 {//从NSDate中取出年月日，时分秒，但是只能取一次

        year
 = [[overdate substringWithRange:NSMakeRange(0, 4)] intValue]; 

        month
 = [[overdate substringWithRange:NSMakeRange(5, 2)] intValue]; 

        day
 = [[overdate substringWithRange:NSMakeRange(8, 2)] intValue]; 

        hour
 = [[overdate substringWithRange:NSMakeRange(11, 2)] intValue]; 

        minute
 = [[overdate substringWithRange:NSMakeRange(14, 2)] intValue]; 

        second
 = [[overdate substringWithRange:NSMakeRange(17, 2)] intValue]; 

        timeStart=
 NO; 

    }

      

    [endTime
 setYear:year]; 

    [endTime
 setMonth:month]; 

    [endTime
 setDay:day]; 

    [endTime
 setHour:hour]; 

    [endTime
 setMinute:minute]; 

    [endTime
 setSecond:second]; 

    NSDate
 *overTime = [cal dateFromComponents:endTime]; //把目标时间装载入date

    //用来得到具体的时差，是为了统一成北京时间

    unsigned
int

unitFlags = NSYearCalendarUnit| NSMonthCalendarUnit| NSDayCalendarUnit| NSHourCalendarUnit| NSMinuteCalendarUnit| NSSecondCalendarUnit;

    NSDateComponents
 *d = [cal components:unitFlags fromDate:today toDate:overTime options:0]; 

    NSString
 *t = [NSString stringWithFormat:@"%d",
 [d day]]; 

    NSString
 *h = [NSString stringWithFormat:@"%d",
 [d hour]]; 

    NSString
 *fen = [NSString stringWithFormat:@"%d",
 [d minute]]; 

    if([d
 minute] < 10) { 

        fen
 = [NSString stringWithFormat:@"0%d",[d
 minute]]; 

    }

    NSString
 *miao = [NSString stringWithFormat:@"%d",
 [d second]]; 

    if([d
 second] < 10) { 

        miao
 = [NSString stringWithFormat:@"0%d",[d
 second]]; 

    }

//   
 NSLog(@"===%@天 %@:%@:%@",t,h,fen,miao); 

    [_longtime
 setText:[NSString stringWithFormat:@"%@天
 %@:%@:%@",t,h,fen,miao]];

    if([d
 second] > 0) { 

        //计时尚未结束，do_something

//       
 [_longtime setText:[NSString stringWithFormat:@"%@:%@:%@",d,fen,miao]]; 

    }
else

if([d
 second] == 0) { 

        //计时结束
 do_something 

          

    }
else{

//计时器失效

        [theTimer
 invalidate]; 

    }

      

}