Count character Occurrences in a string

[kareninstructor]

I have seen this question many times so thought it would be good to post the following code. There are two versions of the code as per below.

using System;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace CountCharacters
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// With encoding
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
            //string items = "AĄBCČDEĘĖFGHIĮYJKLMNOPRSŠTUŲŪVZŽ";

            Encoding iso = Encoding.GetEncoding("ISO-8859-1");
            Encoding utf8 = Encoding.UTF8;
            byte[] utfBytes = utf8.GetBytes(textBox1.Text);
            byte[] isoBytes = Encoding.Convert(utf8, iso, utfBytes);
            string itemsTranslated = iso.GetString(isoBytes);

            var characterGroup = (
                from chr in itemsTranslated.ToCharArray()
                group chr by chr into grp
                select new
                {
                    Letter = grp.Key,
                    Occurrences = grp.Count(),
                    Code = Convert.ToInt32((int)grp.Key)
                })
                .ToList()
                .OrderBy((item) => item.Letter.ToString());

            var results = (from item in characterGroup select item).ToList();

            dataGridView1.DataSource = results;
        }

        /// <summary>
        /// Without encoding
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            var characterGroup = (
                from chr in textBox1.Text.ToCharArray()
                group chr by chr into grp
                select new
                {
                    Letter = grp.Key,
                    Occurrences = grp.Count(),
                    Code = Convert.ToInt32((int)grp.Key)
                })
                .ToList()
                .OrderBy((item) => item.Letter.ToString());

            dataGridView1.DataSource = (from item in characterGroup select item).ToList();

        }
    }
}

Full source in VS2013