ISO Swift Dates

import Foundation

public extension NSDate {
    public class func ISOStringFromDate(date: NSDate) -> String {
        var dateFormatter = NSDateFormatter()
        dateFormatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
        dateFormatter.timeZone = NSTimeZone(abbreviation: "GMT")
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS"
        
        return dateFormatter.stringFromDate(date).stringByAppendingString("Z")
    }
    
    public class func dateFromISOString(string: String) -> NSDate {
        var dateFormatter = NSDateFormatter()
        dateFormatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
        dateFormatter.timeZone = NSTimeZone.localTimeZone()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
        
        return dateFormatter.dateFromString(string)
    }
}