如何计算两个日期之间的差异？

Question

如何计算2010年1月1日至(例如)2010年2月3日之间的天数？

Answer 1

NSDate *date1 = [NSDate dateWithString:@"2010-01-01 00:00:00 +0000"];
NSDate *date2 = [NSDate dateWithString:@"2010-02-03 00:00:00 +0000"];

NSTimeInterval secondsBetween = [date2 timeIntervalSinceDate:date1];

int numberOfDays = secondsBetween / 86400;

NSLog(@"There are %d days in between the two dates.", numberOfDays);

编辑:

请记住,NSDate对象代表精确的时刻,它们没有任何相关的时区信息.当您使用例如一个字符串转换为一个日期NSDateFormatter,该NSDateFormatter转换时间从配置的时区.因此,两个NSDate对象之间的秒数始终与时区无关.

此外,此文档指定Cocoa的时间实现不考虑闰秒,因此如果您需要这样的准确性,您将需要推出自己的实现.

Answer 2

你可能想要使用这样的东西:

NSDateComponents *components;
NSInteger days;

components = [[NSCalendar currentCalendar] components: NSDayCalendarUnit 
        fromDate: startDate toDate: endDate options: 0];
days = [components day];

我相信这种方法可以解决诸如夏令时变化的日期等情况.

Answer 3

NSTimeInterval diff = [date2 timeIntervalSinceDate:date1]; // in seconds

其中,date1和date2是NSDate的.

另外,请注意以下定义NSTimeInterval:

typedef double NSTimeInterval;

Answer 4

看看这个.它使用iOS日历来计算夏令时,闰年.您可以将字符串和条件更改为包含小时和天的分钟.

+(NSString*)remaningTime:(NSDate*)startDate endDate:(NSDate*)endDate
{
    NSDateComponents *components;
    NSInteger days;
    NSInteger hour;
    NSInteger minutes;
    NSString *durationString;

    components = [[NSCalendar currentCalendar] components: NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute fromDate: startDate toDate: endDate options: 0];

    days = [components day];
    hour = [components hour];
    minutes = [components minute];

    if(days>0)
    {
        if(days>1)
            durationString=[NSString stringWithFormat:@"%d days",days];
        else
            durationString=[NSString stringWithFormat:@"%d day",days];
        return durationString;
    }
    if(hour>0)
    {        
        if(hour>1)
            durationString=[NSString stringWithFormat:@"%d hours",hour];
        else
            durationString=[NSString stringWithFormat:@"%d hour",hour];
        return durationString;
    }
    if(minutes>0)
    {
        if(minutes>1)
            durationString = [NSString stringWithFormat:@"%d minutes",minutes];
        else
            durationString = [NSString stringWithFormat:@"%d minute",minutes];

        return durationString;
    }
    return @""; 
}