webViewDidFinish

webViewDidFinish

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        
        let css = "body { background-color : #ff0000 }"
        
        let js = "var style = document.createElement('style'); style.innerHTML = '\(css)'; document.head.appendChild(style);"
        
        webView.evaluateJavaScript(js, completionHandler: nil)
}