UILabel extension for localization

UILabelLocalizationExtension.swift

extension UILabel {
    
    func set(key: LocalizationKey) {
        localizationKey = key
        text = key.string
    }
    
    private struct AssociatedKeys {
        static var localizationKey = "nsh_localizationKey"
    }
    
    var localizationKey: LocalizationKey? {
        get {
            return objc_getAssociatedObject(self, &AssociatedKeys.localizationKey) as? LocalizationKey
        }
        
        set {
            if let newValue = newValue {
                objc_setAssociatedObject(self, &AssociatedKeys.localizationKey, newValue as LocalizationKey?,
                                         .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
            }
        }
    }
}