Get Height of contentWebView WKWebView

import WebKit
class HomePageVC: BaseVC, ControllerType {
    @IBOutlet weak var webViewContent: WKWebView!

    func initWebView() {
        self.webViewContent.scrollView.isScrollEnabled = false
        self.webViewContent.scrollView.bounces = false
        self.webViewContent.scrollView.bouncesZoom = false

        let contentHtml: String = "<html>......" // Change with content  html
        // or change loadUrl not htmlString if needed
        self.webViewContent.loadHTMLString(resContent, baseURL: Bundle.main.bundleURL)
        self.webViewContent.tag = 0
        self.webViewContent.navigationDelegate = self // this needed to get navigation actions
    }
}

extension HomePageVC : WKNavigationDelegate {

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        let idTag: Int = webView.tag
        switch idTag {
        case 0:
            // When webView loaded get the height of page from a JS command and use the height on constraint
            self.webViewContent.evaluateJavaScript("document.readyState", completionHandler: { (complete, error) in
            if complete != nil {
                self.webViewContent.evaluateJavaScript("document.body.scrollHeight", completionHandler: { (height, error) in
                    if let h = height as? CGFloat {
                        self.heightConstrantWebViewcontainer.constant = h
                    }

                })
            }

            })

            break
        case 1:
            let sz = self.newsMediaContainerView.frame.size
            webView.frame.size = sz
            break
        default:
            print("UnHandled webView[\(idTag)]")
        }
    }
    ...
}