ASPXGRIDView FIND Checkbox

foreach (GridViewRow row in GridView1.Rows)
      {
          if (((CheckBox)row.FindControl("checkbox1")) is CheckBox)
          {
              if (((CheckBox)row.FindControl("checkbox1")).Checked == true)
              {
              //do somthing
              }
              else
              {
                  //do somthing
              }
          }
      }