Swift NSUserDefaults UIColor extension

## NSUserDefaults+UIColor.swift
extension NSUserDefaults {

    func colorForKey(key: String) -> UIColor? {
        var color: UIColor?
        if let colorData = dataForKey(key) {
            color = NSKeyedUnarchiver.unarchiveObjectWithData(colorData) as? UIColor
        }
        return color
    }

    func setColor(color: UIColor?, forKey key: String) {
        var colorData: NSData?
        if let color = color {
            colorData = NSKeyedArchiver.archivedDataWithRootObject(color)
        }
        setObject(colorData, forKey: key)
    }

}