Extension

localizedKey.swift

extension UILabel {
    @IBInspectable var localizedKey: String? {
        set {
            if let s = newValue {
                text = NSLocalizedString(s, comment:"")
            }

        }
        get {
            return text
        }
    }
}

extension UIButton {
    @IBInspectable var localizedKey: String? {
        set {
            if let s = newValue {
                setTitle(NSLocalizedString(s, comment:""), forState: .Normal)
            }
            
        }
        get {
            return titleLabel?.text
        }
    }
}