ASP.NET ListView Get Item

=================== .aspx ==========================================

<asp:ListView ID="lvEvent" runat="server" />

...
<asp:CheckBox ID="CheckBox1" runat="server" />

=================== .cs ==========================================

ListViewItem li = lvEvent.Items[index];
CheckBox cb = (CheckBox)li.FindControl("CheckBox1");
cb.Checked = true;