Get Count of Selected CheckBoxes in GridView Row on Button Click in ASP.Net

Here I have created sample that shows the number of selected row count.

<div>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:CheckBox ID="chkHobby" runat="server" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:BoundField DataField="Hobby" HeaderText="Hobby" ItemStyle-Width="150px" ReadOnly="true" />
        </Columns>
    </asp:GridView>
    <asp:Button Text="Get Selected Count" runat="server" OnClick="GetSelectedCount" /><br />
    <br />
    <asp:Label ID="lblCount" runat="server" />
</div>

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        this.BindGrid();
    }
}

private void BindGrid()
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT [HobbyId], [Hobby], [IsSelected] FROM Hobbies"))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    GridView1.DataSource = dt;
                    GridView1.DataBind();
                }
            }
        }
    }
}

protected void GetSelectedCount(object sender, EventArgs e)
{
    int count = 0;
    foreach (GridViewRow row in GridView1.Rows)
    {
        if (((CheckBox)row.FindControl("chkHobby")).Checked)
        {
            count++;
        }
    }
    lblCount.Text = "Selected count : " + count;
}

Screenshot