// [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerFireMethod:) userInfo:nil repeats:YES]; ?// - (void)timerFireMethod:(NSTimer *)theTimer { ????BOOL timeStart = YES; ????NSCalendar *cal = [NSCalendar currentCalendar];//定義一個NSCalendar對象 ????NSDateComponents *endTime = [[NSDateComponents alloc] init];??? //初始化目標時間... ????NSDate *today = [NSDate date];??? //得到當前時間 ?????????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) {//從NSDate中取出年月日，時分秒，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]; //把目標時間裝載入date ????//用來得到具體的時差，是為了統一成北京時間 ????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]  0) { ????????//計時尚未結束，do_something //??????? [_longtime setText:[NSString stringWithFormat:@"%@:%@:%@",d,fen,miao]]; ????} else if([d second] == 0) { ????????//計時結束 do_something ?????????????} else{ //計時器失效????????[theTimer invalidate]; ????} ?????}