How to Evaluate JavaScript with Swift - Getting nil for all values (evertime: even is path is correct)

Question

I'm trying to simply evaluate the Javascript, but it comes up with an error. I simply want to print everything inside of 'container title'.

Hey I'm getting an error with this code:

WebView.evaluateJavaScript("document.getElementsByClassName('mdl-js').getElementsByClassName('container title')[0].innerHTML"){ (value, error) in
if error != nil {
    print("Error = \(String(describing: error))")
} else {
    print("Success = \(String(describing: value))")
}

}

(Note - I know how to evaluate Javascript with Swift, but can't seem to figure this one out)

I'm Getting nil for all values (evertime: even is path is correct).

My WebView is set up like this:

    let preferences = WKPreferences()
    preferences.javaScriptEnabled = true
    preferences.javaScriptCanOpenWindowsAutomatically = true

    // Create a configuration for the preferences
    let configuration = WKWebViewConfiguration()
    configuration.preferences = preferences

    voiceWebView = WKWebView(frame: CGRect(x: page3View.frame.width * 0.0, y: page3View.frame.height * 0.0, width: page3View.frame.width, height: page3View.frame.height), configuration: configuration)
    voiceWebView.backgroundColor = UIColor.clear
    voiceWebView.uiDelegate = self
    voiceWebView.navigationDelegate = self
    voiceWebView.isUserInteractionEnabled = true
    voiceWebView.alpha = 1.0

    page3View.insertSubview(voiceWebView, at: 0)
    page3View.bringSubview(toFront: voiceWebView)

    voiceWebView.load(URLRequest(url: NSURL(string:"https://test.com")! as URL))

Update:

This prints nil

document.getElementsByClassName('container title').innerHTML

Also

document.getElementsByClassName('container title')[0].innerHTML

This alone error out this -