keeping GridView checkbox state when posting back

I have a GridView which with a CheckBox in a TemplateField.

When I check something and hit the submit button, the items that I have checked are not check on the postback.

I tried using EnableViewState and that did not help.

How can this be fixed?

    <asp:Button ID="btnSubmit" runat="server" Text="Submit" />

    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
        <Columns>               
             <asp:TemplateField HeaderText="SELECT">
                <ItemTemplate>
                   <asp:CheckBox ID="CheckBox1" runat="server"/>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:BoundField DataField="ICAO" HeaderText="ICAO" />
            <asp:BoundField DataField="IATA" HeaderText="IATA" />
            <asp:BoundField DataField="AIRPORT_NAME" HeaderText="AIRPORT NAME" />
            <asp:BoundField DataField="CITY" HeaderText="CITY" />
            <asp:BoundField DataField="COUNTRY" HeaderText="COUNTRY" />
            <asp:BoundField DataField="REVISED_DATE" HeaderTex开发者_高级运维t="REVISED DATE" />
            <asp:BoundField DataField="EMAIL_DATE" HeaderText="EMAIL DATE" />          
        </Columns>            
    </asp:GridView>

You need to override LoadViewState and SaveViewState methods to maintain the selection.

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