How to set the encoding to UTF-8 for XmlTextWriter [duplicate]

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• Using StringWriter for XML Serialization 5 answers

This question may have been asked before but my case is a bit different. Since i am using the Stringwriter Function for my XMLwriter

        StringWriter stringWriter = new StringWriter();
        XmlTextWriter writer = new XmlTextWriter(stringWriter) ;

        //Write the root element
        writer.WriteStartDocument();
        writer.WriteStartElement("items");

        //Write sub-elements
        writer.WriteElementString("title", "Unreal Tournament 2003");
        writer.WriteElementString("title", "C&C: Renegade");
        writer.WriteElementString("title", "Dr. Seuss's ABC");

        // end the root element
        writer.WriteEndElement();

        string test = stringWriter.ToString();

        writer.Flush();
        writer.Close();
        stringWriter.Flush();

The above code of mine set encosing to UTF-16, I Need UTF-8. I cannot use the

XmlWriter writer = XmlWriter.Create(stream, settings);

as i am using stringbuilder and not memory stream. So how should i set the encoding. Any suggestions?