How to activate darkmode for the text changed in WkWebViewRenderer?

Issue

I was trying to resize the text in a webView in Xamarin.iOS with a webView-renderer. It works, but my problem is that the dark mode does not work anymore. I have already changed the background of the web view, so it is shown right, but I don’t know how to do it with the text.

  public class NavigationDelegat : WKNavigationDelegate
{
    public override void DidFinishNavigation(WKWebView webView, WKNavigation navigation)
    {
        string Size  "300%"; 
        string text  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust '{0}'", Size);

        WKJavascriptEvaluationResult handler  (NSObject result, NSError err) > {
            if (err ! null)
            {
                System.Console.WriteLine(err);
            }
            if (result ! null)
            {
                System.Console.WriteLine(result);
            }
        };

        webView.EvaluateJavaScript(text, handler);
        webView.Opaque  false;
        webView.BackgroundColor  UIColor.Clear;


    }
}

How to do it? The text is always black, also when darkMode is activated.

Solution

You could have a try with code as follows:

public class NavigationDelegat : WKNavigationDelegate
{
    public override void DidFinishNavigation(WKWebView webView, WKNavigation navigation)
    {
        string Size  "300%"; 
        string textSize  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust '{0}'", Size);
        string TextColor  "#ffffff"; 
        string textColor  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextFillColor  '{0}'", TextColor);

        WKJavascriptEvaluationResult handler  (NSObject result, NSError err) > {
            if (err ! null)
            {
                System.Console.WriteLine(err);
            }
            if (result ! null)
            {
                System.Console.WriteLine(result);
            }
        };

        webView.EvaluateJavaScript(textSize , handler);
        webView.EvaluateJavaScript(textColor, handler);
        webView.Opaque  false;
        webView.BackgroundColor  UIColor.Clear;
    }
}

*Update*\

private class WKwebviewdeleagte : WKNavigationDelegate
{
    public override void DidFinishNavigation(WKWebView webView, WKNavigation navigation)
    {
        base.DidFinishNavigation(webView, navigation);
        if(UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
        {
            string Size  "300%";
            string TextSize  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust '{0}'", Size);
            string TextColor;
            string BackgroundColor;
            if (UITraitCollection.CurrentTraitCollection.UserInterfaceStyle  UIUserInterfaceStyle.Light)
            {
                string textColor  "#666666";
                TextColor  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextFillColor  '{0}'", textColor);
                string backgroundColor  "\"#FFFFFF\"";
                BackgroundColor  String.Format(@"document.body.style.backgroundColor'{0}'", backgroundColor);
            }
            else
            {
                string textColor  "#ffffff";
                TextColor  String.Format(@"document.getElementsByTagName('body')[0].style.webkitTextFillColor  '{0}'", textColor);
                string backgroundColor  "\"#001A1A\"";
                BackgroundColor  String.Format(@"document.body.style.backgroundColor'{0}'", backgroundColor);
            }

            WKJavascriptEvaluationResult handler  (NSObject result, NSError err) > {
                if (err ! null)
                {
                    System.Console.WriteLine(err);
                }
                if (result ! null)
                {
                    System.Console.WriteLine(result);
                }
            };

            webView.EvaluateJavaScript(TextSize, handler);
            webView.EvaluateJavaScript(TextColor, handler);
            webView.EvaluateJavaScript(BackgroundColor, handler);
            //webView.Opaque  false;
            //webView.BackgroundColor  UIColor.Clear;
        }
    }
}

Answered By – Junior Jiang