Check if date falls between 2 dates

extension Date
{
    func isBetween(startDate:Date, endDate:Date)->Bool
    {
         return (startDate.compare(self) == .orderedAscending) && (endDate.compare(self) == .orderedDescending)
    }
}

Swift 2

For a better answer see Swift ≧ 3.

You already have the code for conversion of your date string in KeysData to NSDate. Assuming you have the two dates in startdate and enddate, all you have to do is check if the current date is in between:

let startDate = ...
let endDate = ...

NSDate().isBetween(date: startDate, andDate: endDate)

extension NSDate {
    func isBetweeen(date date1: NSDate, andDate date2: NSDate) -> Bool {
        return date1.compare(self) == self.compare(date2)
    }
}

Edit: If you want to perform an inclusive range check, use this condition:

 extension NSDate {
    func isBetween(date date1: NSDate, andDate date2: NSDate) -> Bool {
        return date1.compare(self).rawValue * self.compare(date2).rawValue >= 0
    }
}

For Swift 4.2+ I used this extension based on answer above:

extension Date {
    func isBetween(_ date1: Date, and date2: Date) -> Bool {
        return (min(date1, date2) ... max(date1, date2)) ~= self
    }
}

But be careful. If this extension doesn't include your start date (date1), then check the time of your dates. May be you'll need to cut the time from dates to fix it. For example, like this:

let myDateWithoutTime = Calendar.current.startOfDay(for: myDate)

Swift ≧ 3

Swift 3 makes this a lot easier.

let fallsBetween = (startDate ... endDate).contains(Date())

Now that NSDate is bridged to the value type Date and Date conforms to Comparable we can just form a ClosedRange<Date> and use the contains method to see if the current date is included.

Caveat: endDate must be greater or equal startDate. Otherwise the range could not be formed and the code would crash with a fatalError.

This is safe:

extension Date {
    func isBetween(_ date1: Date, and date2: Date) -> Bool {
        return (min(date1, date2) ... max(date1, date2)).contains(self)
    }
}