两个NSDate对象之间的天数 [英] Number of days between two NSDate objects

问题描述

我正在尝试比较两天的NSDate对象，我在第一次使用NSDateComponents来计算我的两个日期对象之间的差异，但它工作正常。

I'm trying to compare two days of NSDate objects, I used at the first time NSDateComponents to calculate difference between my two dates Objects, but it is working correctly.

    NSString *dateStr =@"2012-11-05 15:00:00";
    NSDate *date = [dateFormat dateFromString:dateStr];
    NSDateComponents *datesDiff = [calendar components: NSDayCalendarUnit
                                              fromDate: date
                                                toDate: [NSDate date]
                                               options: 0];

这不能解决我的问题。实际上，当date1 = 2012-11-05 23:00:00和date2 = 2012-11-06 10:00:00时，拖曳日期之间的差异是0天和11小时。
我正在寻找能让我发现日期变化的东西，换句话说，当date1 = 2012-11-05 23:00:00和date2 = 2012-11-06 00:01:00时，有一天差异。

That does not resolve my problem. Indeed when date1 = 2012-11-05 23:00:00 and date2 = 2012-11-06 10:00:00, the difference between the tow dates is 0 day and 11 hours. I am looking for something that allows me to detect day changes, in other words when date1 = 2012-11-05 23:00:00 and date2 = 2012-11-06 00:01:00, there's one day diffrence.

如果有人知道解决方案，我会欢迎他的建议。
提前致谢

If someone knows the solution for that, i would welcome his suggestion. Thanks in advance

推荐答案

我认为你正在寻找这个（来自日期和时间编程指南）：

I think you are looking for this (from the Date and Time Programming Guide):

清单13两个日期之间的天数，作为中间夜数

Listing 13 Days between two dates, as the number of midnights between

@implementation NSCalendar (MySpecialCalculations)

-(NSInteger)daysWithinEraFromDate:(NSDate *) startDate toDate:(NSDate *) endDate
{
     NSInteger startDay=[self ordinalityOfUnit:NSDayCalendarUnit
          inUnit: NSEraCalendarUnit forDate:startDate];
     NSInteger endDay=[self ordinalityOfUnit:NSDayCalendarUnit
          inUnit: NSEraCalendarUnit forDate:endDate];
     return endDay-startDay;
}
@end

编辑：Swift版本：

extension NSCalendar {
    func daysWithinEraFromDate(startDate: NSDate, endDate: NSDate) -> Int {
        let startDay = self.ordinalityOfUnit(.Day, inUnit: NSCalendarUnit.Era, forDate: startDate)
        let endDay = self.ordinalityOfUnit(.Day, inUnit: NSCalendarUnit.Era, forDate: endDate)
        return endDay - startDay
    }
}

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