Ali Ali - 5 months ago 14
iOS Question

Number of days between two NSDate objects

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];


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.

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

Answer

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

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

EDIT: Swift version:

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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