查找两个日期之间的精确差异

Question

我想要对日期比较进行一些更改。

在我的应用程序中，我比较两个日期并获取天数差异，但如果只有一天差异，系统会显示 0 作为天数差异。

NSDateFormatter *date_formater=[[NSDateFormatter alloc]init];
[date_formater setDateFormat:@"MMM dd,YYYY"];

NSString *now=[NSString stringWithFormat:@"%@",[date_formater stringFromDate:[NSDate date]]];
LblTodayDate.text = [NSString stringWithFormat:@"%@",[NSString stringWithFormat:@"%@",now]];

NSDate *dateofevent = [[NSUserDefaults standardUserDefaults] valueForKey:@"CeremonyDate_"];
NSDate *endDate =dateofevent;

NSDate *startDate = [NSDate date];

gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
unsigned int unitFlags = NSDayCalendarUnit;

NSDateComponents *components = [gregorian components:unitFlags fromDate:startDate toDate:endDate options:0];

int days = [components day];

我找到了一些解决方案，如果我们将时间设置为 00:00:00 进行比较，那么它会向我显示正确的答案，我不知道是对还是错。

Answer 1

我通常会找出以秒为单位的差异并计算 ceil(diffInSeconds / 86400) 。

Answer 2

尝试使用此代码获取两个不同的日期和时间。

  NSDateFormatter* dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
        [dateFormatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"] autorelease]];
        [dateFormatter setDateFormat:@"mm:ss"];

        NSDate* firstDate = [dateFormatter dateFromString:@"04:45"];
        NSDate* secondDate = [dateFormatter dateFromString:@"05:00"];

        NSTimeInterval timeDifference = [secondDate timeIntervalSinceDate:firstDate];
        NSLog(@"%f",timeDifference);

我希望这段代码对你有用。

Answer 3

这里有一个完美的解决方案来查找两个日期之间的差异

- (NSString *)calculateDuration:(NSDate *)oldTime secondDate:(NSDate *)currentTime
{
    NSString *timeSincePost;
 NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSCalendarUnit unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
    NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:oldTime toDate:currentTime options:0];

    NSInteger year = [dateComponents year];
    NSInteger month = [dateComponents month];
    NSInteger day = [dateComponents day];
    NSInteger hour = [dateComponents hour];
    NSInteger minute = [dateComponents minute];
    NSInteger second = [dateComponents second];

    if (year) {
        timeSincePost = [NSString stringWithFormat:@"%ld%@", (long)year,[[kAppDelegate languageBundle] localizedStringForKey:@"y" value:@"" table:nil]];
    }
    else if (month) {
         timeSincePost = [NSString stringWithFormat:@"%ld%@", (long)month,[[kAppDelegate languageBundle] localizedStringForKey:@"M" value:@"" table:nil]];
    }
    if(day) {
        timeSincePost = [NSString stringWithFormat:@"%ld%@", (long)day,[[kAppDelegate languageBundle] localizedStringForKey:@"d" value:@"" table:nil]];
    }
    else if(hour) {
        timeSincePost = [NSString stringWithFormat: @"%ld%@", (long)hour,[[kAppDelegate languageBundle] localizedStringForKey:@"H" value:@"" table:nil]];
    }
    else if(minute) {
        timeSincePost = [NSString stringWithFormat: @"%ld%@", (long)minute,[[kAppDelegate languageBundle] localizedStringForKey:@"m" value:@"" table:nil]];
    }
    else if(second)
        timeSincePost = [NSString stringWithFormat: @"%ld%@", (long)second,[[kAppDelegate languageBundle] localizedStringForKey:@"s" value:@"" table:nil]];

    return timeSincePost;
}

并使用两个参数作为 NSDate 调用上面的函数

NSString *duration = [self calculateDuration:postDate secondDate:[NSDate date]];
lblPostTime.text = duration;

注意:: postDate 是 FirstDate &第二个日期是当前日期..

Answer 4

我认为这不正确，请将时间设置为 00:00:00。

可能您得到的差异小于 24 小时，这就是为什么四舍五入而您的时间为 0 天。

亚历山大的解决方案是正确的，所以使用像这样的解决方案 -

这对我来说也很好。

NSDate *endDate=[dateFormat dateFromString:now];
        NSTimeInterval interval = [CeremonyDate timeIntervalSinceDate:endDate];
        int diff=interval/86400;//for converting seconds into days.

同样的问题是对你在这里得到的数字进行四舍五入，但你可以用一种不稳定的方式解决这个问题。