using System;

using System.IO;

using System.Text;

using System.Xml;

using System.Xml.Serialization;

​

​

class Program

{

    static void Main()

    {

        var sample = new XmlSample

        {

            Element1 = "foo",

            Element2 = "bar"

        };

​

        var xml = sample.Serialize();

​

        Console.WriteLine(xml);

    }

}

​

[XmlRoot("XMLSample", Namespace = "http://crd.gov.pl/wzor/")]

public class XmlSample

{

    [XmlElement]

    public string Element1 { get; set; }

​

    [XmlElement(Namespace = "http://crd.gov.pl/xml/schematy/")]

    public string Element2 { get; set; }

​

    public string Serialize()

    {

        var serializer = new XmlSerializer(GetType());

​

        var xsn = new XmlSerializerNamespaces();

        xsn.Add("xsi", "http://www.w3.org/2001/");

        xsn.Add("etd", "http://crd.gov.pl/xml/schematy/");

​

        var settings = new XmlWriterSettings

        {

            Indent = true

        };

​

        using var sw = new Utf8StringWriter();

        using var xw = XmlWriter.Create(sw, settings);

        serializer.Serialize(xw, this, xsn);

        return sw.ToString();

    }

}

​

public class Utf8StringWriter : StringWriter

{

    public override Encoding Encoding => new UTF8Encoding(false);

}