NSDate 输出错误的日期

Question

我正在使用NSDate 和NSDateFormatter 创建一个特定日期的倒数计时器。唯一的问题是，当我以不同的格式运行代码时，日期会混乱。这是运行良好的原始代码。

- (void)updateCountdown {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd"];
    NSDate *startingDate = [dateFormatter dateFromString:@"2014-10-08"];
    NSDate *endingDate = [NSDate date];

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit;
    NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:startingDate toDate:endingDate options:0];

    NSInteger days     = [dateComponents day];
    NSInteger months   = [dateComponents month];
    NSInteger years    = [dateComponents year];
    NSInteger hours    = [dateComponents hour];
    NSInteger minutes  = [dateComponents minute];
    NSInteger seconds  = [dateComponents second];
    NSString *countdownText = [NSString stringWithFormat:@"%ld Years %ld Months %ld Days %ld Hours %ld Minutes %ld Seconds", (long)days, (long)months, (long)years, (long)hours, (long)minutes, (long)seconds];

    _countdown.text = countdownText;

    [self performSelector:@selector(updateCountdown) withObject:nil afterDelay:1];
}

但是说我想删除年份，所以我像这样更改代码：

- (void)updateCountdown {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd"];
    NSDate *startingDate = [dateFormatter dateFromString:@"2014-10-08"];
    NSDate *endingDate = [NSDate date];

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit;
    NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:startingDate toDate:endingDate options:0];

    NSInteger days     = [dateComponents day];
    NSInteger months   = [dateComponents month];
    NSInteger hours    = [dateComponents hour];
    NSInteger minutes  = [dateComponents minute];
    NSInteger seconds  = [dateComponents second];
    NSString *countdownText = [NSString stringWithFormat:@"%ld Months %ld Days %ld Hours %ld Minutes %ld Seconds", (long)days, (long)months, (long)hours, (long)minutes, (long)seconds];

    _countdown.text = countdownText;

    [self performSelector:@selector(updateCountdown) withObject:nil afterDelay:1];
}

现在突然间，数据被整整一个月搞砸了。我该如何解决这个问题？

还有为什么输出 0 years -1months 0 days -2 Hours .. 就像为什么那里有 (-) 一样？谢谢！

Answer 1

您的论点顺序错误 首先你有

[NSString stringWithFormat:@"%ld Years %ld Months %ld Days %ld Hours %ld Minutes %ld Seconds", (long)days, (long)months, (long)years, (long)hours, (long)minutes, (long)seconds];

你正在输入

• 占位符年的天数
• 数年变成数天

那么你有

[NSString stringWithFormat:@"%ld Months %ld Days %ld Hours %ld Minutes %ld Seconds", (long)days, (long)months, (long)hours, (long)minutes, (long)seconds];

你正在输入

• 占位符月份的天数
• 几个月到位举行几天 只有最后 3 个符合您的预期