ios - Two prototype cells in one section -

i have 2 prototype cells. 1 appears if messagesarray[indexpath.row] value "", other if value contains characters. 1 of cells' row height greater second , contains additional variables. they're both hooked own cell classes , have own cell identifiers. want them both coexist in same tableview, under 1 section, i'm struggling achieve that. keep getting fatal error: array index out of range. array value being populated async db request, explanation.

what doing wrong/how can successfully?

var messagesarray = [string]()  override func viewdidload() {         super.viewdidload()  var query = pfquery(classname: "class") query.findobjectsinbackgroundwithblock { (objects, error) -> void in             if error == nil {                  if let objects = objects {                     object in objects {                         if let message = object["message"] as? string {                             self.messagesarray.append(message)                         }                     }                  }            } else {                     println(error)                 }          }    }    func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell {          if self.messagesarray[indexpath.row] == "" {              var cell = tableview.dequeuereusablecellwithidentifier("cellone", forindexpath: indexpath) as! cellone              return cell          } else {              var cell = tableview.dequeuereusablecellwithidentifier("celltwo", forindexpath: indexpath) as! celltwo              return cell         }       } 

edit: if messagesarray[indexpath.row] == value other "" (there's message), first cell in message displayed in larger second cell , displayed uilabel doesn't exist in second cell.

if using dynamic cells must not have 2 prototype cells on tableview, 1 needed job done.

var messagesarray = [string]()  override func viewdidload() {     super.viewdidload()         var query = pfquery(classname: "class")     query.findobjectsinbackgroundwithblock { (objects:[anyobject]?, error:nserror) -> void in         if error == nil         {                if let objects = objects as? [pfobject]                {                    object in objects                    {                     var message = object["message"]                     self.messagesarray.append(message)                     self.tableview.reloaddata()                 }              }           }          else         {             println(error)         }     } }    func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell {           var cell = tableview.dequeuereusablecellwithidentifier("cellone", forindexpath: indexpath) as! cellone           var data = self.messagesarray[indexpath.row]            cell.textlabel.text = data 

}