unresolved identifier in Swift -

i can not resolve problem in swift , xcode

error swift use of unresolved identifier

// configure cell...

    cell.textlabel?.text = restaurantnames[indexpath.row]      cell.thumbnailimageview.image = uiimage(named: restaurantimages [indexpath.row])      return cell  } 

in cellforrowatindexpath method, have identify tableviewcell storyboard id, in case cell

override func viewdidload() {      tableview.registerclass(customtableviewcell.self, forcellreuseidentifier: "cell") }  func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath)->uitableviewcell {     var cell:customtableviewcell? = tableview.dequeuereusablecellwithidentifier("cell", forindexpath: indexpath) as? customtableviewcell      cell!.textlabel?.text = restaurantnames[indexpath.row]     cell!.thumbnailimageview.image = uiimage(named: restaurantimages [indexpath.row])     return cell! }