Find number of days between two dates.

+ (int)daysBetweenFromDate:(NSDate*)fromDateTime toDate:(NSDate*)toDateTime

{

    NSDate *fromDate;

    NSDate *toDate;

    //initialize the calender

    NSCalendar *calendar = [NSCalendar currentCalendar];

    //Returns by reference the starting time and duration of a given calendar unit that contains a given date.

    [calendar rangeOfUnit:NSDayCalendarUnit startDate:&fromDate

                 interval:NULL forDate:fromDateTime];

    

    [calendar rangeOfUnit:NSDayCalendarUnit startDate:&toDate

                 interval:NULL forDate:toDateTime];

    //Returns, as an NSDateComponents object using specified components, the difference between two supplied dates.

    NSDateComponents *difference = [calendar components:NSDayCalendarUnit

                                               fromDate:fromDate toDate:toDate options:0];

    

    return [difference day];

}