Add NSDate support to NSUserDefaults

NSUserDefaultsNSDateExtensions.swift

import Foundation

// ISO Formatting
extension NSDate {
    static func ISOStringFromDate(date: NSDate) -> String {
        let 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")
    }
    
    static func dateFromISOString(string: String) -> NSDate? {
        let 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)
    }
    
}

// NSUserDefaults + NSDate
extension NSUserDefaults {
    func dateForKey(defaultName: String) -> NSDate? {
        if let stringForKey = self.stringForKey(defaultName) {
            return NSDate.dateFromISOString(stringForKey)
        }
        return nil
    }
    
    func setDate(date: NSDate, forKey defaultName:String) {
        self.setValue(NSDate.ISOStringFromDate(date), forKey: defaultName)
    }
}