I want to maintain selected checkboxes in gridview while paging

[Pwintwahsoe]

 protected void GridView2_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        
        GridView2.PageIndex = e.NewPageIndex;
        selectedCheckboxes();
        BindGrid();
    }
private void BindGrid()
    {
        try
        {
            lblError.Visible = false;
            SqlCommand cmd2 = sqlcon.CreateCommand();
            cmd2.CommandText = "SELECT * FROM ImportData order by UserID";

            DataSet sds = new DataSet();

            SqlDataAdapter sda = new SqlDataAdapter(cmd2);

            sda.Fill(sds, "ImportData");
            GridView2.DataSource = sds.Tables["ImportData"].DefaultView;
            GridView2.DataBind();
        }
        catch (Exception ex)
        {
            lblError.Visible = true;
            lblError.Text = ex.Message;
        }

    }
      <asp:GridView
    ID="GridView2"
    OnPageIndexChanging="GridView2_PageIndexChanging"
    runat="server"
    AutoGenerateColumns="False"
    BorderStyle="Solid"
    CellPadding="4"
    DataKeyNames="UserID"
    BorderColor="Silver"
    BorderWidth="1px"
    Width="300px"
    AllowPaging="True"
    
    PageSize="4"
    ShowHeader="False">

<Columns>

<asp:TemplateField>

<ItemTemplate>



<asp:CheckBox
    ID="chk1"
    runat="server"
    Text='<%#DataBinder.Eval( Container.DataItem, "UserID") +"      "+DataBinder.Eval( Container.DataItem, "Name") %>' />
     

</ItemTemplate>

</asp:TemplateField>

</Columns>

<HeaderStyle HorizontalAlign="Left" />
 

</asp:GridView>      
        <asp:HiddenField ID="hiddenCatIDs" runat="server" Visible="true"/>
    </div>

 protected void selectedCheckboxes()
    {
       
        string[] hiddenIDs = new string[] { };

        if (hiddenCatIDs.Value != string.Empty)
        {
            hiddenIDs = hiddenCatIDs.Value.Split(new char[] { '|' });
        }

        ArrayList arrIDs = new ArrayList();

        string CatID = "0";

        if (hiddenIDs.Length != 0)
        {
            arrIDs.AddRange(hiddenIDs);
        }

        CheckBox chk;

        foreach (GridViewRow rowItem in GridView2.Rows)
        {

            chk = (CheckBox)(rowItem.Cells[0].FindControl("chk1"));
            CatID = GridView2.DataKeys[rowItem.RowIndex]["UserID"].ToString();

            if (chk.Checked)
            {
                Response.Write("chk.Checked in if :" + chk.Checked + "<br />");
                if (!arrIDs.Contains(CatID))
                {
                    arrIDs.Add(CatID);
                }
            }
            else
            {
                Response.Write("chk.Checked in else :" + chk.Checked + "<br />");
                if (arrIDs.Contains(CatID))
                {
                    arrIDs.Remove(CatID);
                }
            }
        }

        // ArrayList collection converted into string array.
        hiddenIDs = (string[])arrIDs.ToArray(typeof(String));


        // Join function of string array is used here to create a '|' separated string that can be stored in the hiddenCatIDs control.
        // HiddenField Control is used here to maintain the checkbox state while GridView paging.
        hiddenCatIDs.Value = string.Join("|", hiddenIDs);

        Response.Write(hiddenCatIDs.Value);
    }
    protected void btnMultipleRowDelete_Click(object sender, EventArgs e)
    {
        // Looping through all the rows in the GridView
        foreach (GridViewRow row in GridView1.Rows)
        {
            CheckBox checkbox = (CheckBox)row.FindControl("cbRows");

            //Check if the checkbox is checked.
            //value in the HtmlInputCheckBox's Value property is set as the //value of the delete command's parameter.
            if (checkbox.Checked)
            {
                // Retreive the User ID
                int UserID = Convert.ToInt32(GridView1.DataKeys[row.RowIndex].Value);
                // Pass the value of the selected User  ID to the Delete //command.
                SqlDataSource1.DeleteParameters["UserID"].DefaultValue = UserID.ToString();
               
                SqlDataSource1.Delete();
            }
        }
    }