     /**
         Initializes a new item using the specified image, style and handler
      */
-    public convenience init(image: UIImage?, style: UIBarButtonItemStyle, handler: (UIBarButtonItem) -> Void) {
+    public convenience init(image: UIImage?, style: UIBarButtonItemStyle, handler: ((UIBarButtonItem) -> Void)? = nil) {
         self.init(image: image, style: style, target: nil, action: nil)
         initClosureHandler(handler)
     }

    /**
        Initializes a new item using the specified title, style and handler
     */
    public convenience init(title: String?, style: UIBarButtonItemStyle, handler: (UIBarButtonItem) -> Void) {
        self.init(title: title, style: style, target: nil, action: nil)
        initClosureHandler(handler)
    }

    /**
        Initializes a new item containing the specified system item and using the specified handler
     */
    public convenience init(barButtonSystemItem systemItem: UIBarButtonSystemItem, handler: ((UIBarButtonItem) -> Void)? = nil) {
        self.init(barButtonSystemItem: systemItem, target: nil, action: nil)
        initClosureHandler(handler)
    }
