如何得到DataGrid中的各个控件并取值

foreach (DataGridItem i in MyDataGrid.Items)
   {
    checkBox = (CheckBox) i.FindControl ("SelectCheckBox");//SelectCheckBox为控件的ID

    if (checkBox.Checked)
    {
     type = MyDataGrid.Items[index].Cells[1].Text;//DataGrid中某行某列的值Items－行 Cells－列
     dropDownList = (DropDownList) i.FindControl ("subtype");
     subType = dropDownList.SelectedItem.Value.ToString();//提取下拉框选中值的索引Text是取得选中的值
    }

    index += 1 ;
   }