ios - tableView jumping scrolling after reloadData -

my tableview scrolling jumping when reload tableview new data. here code cellforrowatindexpath:

func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell {      let section = indexpath.section      let index = indexpath.row      let info = data[sections[section]]![index] conversationmessage       if info.from == .me {          var cell: conversationdialogmetablecell = tableview.dequeuereusablecellwithidentifier("mecell", forindexpath: indexpath) as! conversationdialogmetablecell          cell.backgroundcolor = uicolor.clearcolor()          cell.selectionstyle = .none          cell.messagelabel.text = info.text          return cell      } else if info.from == .other {          var cell: conversationdialogothertablecell = tableview.dequeuereusablecellwithidentifier("othercell", forindexpath: indexpath) as! conversationdialogothertablecell          cell.backgroundcolor = uicolor.clearcolor()          cell.selectionstyle = .none          cell.personname.textcolor = uicolor(hex: 0x6d6d6d)          cell.messagecontainerview.backgroundcolor = uicolor(hex: 0x6d6d6d)          cell.messagecontainerview.layer.cornerradius = 5          cell.messagecontainerview.clipstobounds = true          alamofire.request(.get, info.personimage).response {              (request, response, data, error) in              let image = uiimage(data: data!, scale: 1)!              cell.personimage.image = image              cell.personimage.contentmode = uiviewcontentmode.scaleaspectfill              cell.personimage.layer.cornerradius = cell.personimage.frame.height / 2              cell.personimage.clipstobounds = true          }          cell.personname.text = info.personname          cell.personmessage.text = info.text          return cell     }     return uitableviewcell() } 

for first load scrolling smooth, if add new data in tableview , call reloaddata() scrolling jumping when new cells shown.

here code insert new data model:

func client(client: pubnub!, didreceivemessage message: pnmessageresult!) {     if message.data.subscribedchannel == self.channel {         if let messageinfo: anyobject = message.data.message {             let date = (messageinfo["date"] as! string).getdatestring()             let messagetext = messageinfo["message"] as! string             let from: conversationmessage.sendfromtype = (messageinfo["userid"] as! string) == self.userid ? .me : .other             let image = messageinfo["userphoto"] as! string             let name = messageinfo["username"] as! string             if data[date] != nil {                 data[date]!.append(conversationmessage(text: messagetext, from: from, personimage: image, personname: name, date: messageinfo["date"] as! string))             } else {                 data[date] = [conversationmessage(text: messagetext, from: from, personimage: image, personname: name, date: messageinfo["date"] as! string)]             }             section in self.sections {                 self.data[section]! = sorted(self.data[section]!) { utils.comparedatetime($0.date, with: $1.date, order: .orderedascending) }             }             tableview.reloaddata()             tableviewscrolltobottom(false)         }     } } 

maybe happens because of function scroll tableview bottom:

func tableviewscrolltobottom(animated: bool) {     let delay = 0.1 * double(nsec_per_sec)     let time = dispatch_time(dispatch_time_now, int64(delay))      dispatch_after(time, dispatch_get_main_queue(), {        let numberofsections = self.tableview.numberofsections()        let numberofrows = self.tableview.numberofrowsinsection(numberofsections - 1)        if numberofrows > 0 {            let indexpath = nsindexpath(forrow: numberofrows - 1, insection: (numberofsections - 1))            self.tableview.scrolltorowatindexpath(indexpath, atscrollposition: uitableviewscrollposition.bottom, animated: animated)        }     }) } 

one more thing. should cache uploaded images? maybe causing jumping scroll. can me solve issue?