     }
     
     func showHideBackButton(show: Bool) {
-        navigationItem.leftBarButtonItem = show ? UIBarButtonItem(barButtonSystemItem: .Rewind, target: self, action: "goBack:") : nil
+        navigationItem.leftBarButtonItem = show ? UIBarButtonItem(barButtonSystemItem: .Rewind, target: self, action: #selector(DropboxConnectController.goBack(_:))) : nil
     }
     
     func goBack(sender: AnyObject?) {

        
        self.view.backgroundColor = UIColor.whiteColor()
        
        self.cancelButton = UIBarButtonItem(barButtonSystemItem: .Cancel, target: self, action: "cancel:")
        self.navigationItem.rightBarButtonItem = self.cancelButton
    }
    

        return decisionHandler(.Allow)
    }
    
    public func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
        indicator.stopAnimating()
        indicator.removeFromSuperview()
    }
