Return HTML string from the completion handler of the evaluateJavaScript function

I know that I'm not the first one to ask this but I can't solve the problem. I'm trying to take a piece of string from HTML using evaluateJavaScript in Xcode with Swift 3 and the piece of text is called value inside the completion handler, so I did like this:

var userName = String()

   func takeData() {
        webView.evaluateJavaScript("document.querySelectorAll('.name')[0].innerHTML") { (value, error) in

            if let valueName = value as? String {
                self.userName = valueName
            }
            print(value)
            print(error)
        }

    }

print(" The name is : \(self.userName)") 

The problem is that the console just prints: The name is ()