Number of days between two NSDates [duplicate]

Answer 1

Here is an implementation of Brian's function in Swift:

class func daysBetweenThisDate(fromDateTime:NSDate, andThisDate toDateTime:NSDate)->Int?{

    var fromDate:NSDate? = nil
    var toDate:NSDate? = nil

    let calendar = NSCalendar.currentCalendar()

    calendar.rangeOfUnit(NSCalendarUnit.DayCalendarUnit, startDate: &fromDate, interval: nil, forDate: fromDateTime)

    calendar.rangeOfUnit(NSCalendarUnit.DayCalendarUnit, startDate: &toDate, interval: nil, forDate: toDateTime)

    if let from = fromDate {

        if let to = toDate {

            let difference = calendar.components(NSCalendarUnit.DayCalendarUnit, fromDate: from, toDate: to, options: NSCalendarOptions.allZeros)

            return difference.day
        }
    }

    return nil
}