ios - Can't get convertRect: fromView to work -

inside viewcontroller have tableview custom cells. on cellforrow:atindexpath: method i'd access location (rect), according viewcontroller's coordinate system, of uibutton displayed inside specific cell. how thought work:

func tableview(tableview: uitableview,                cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell {      var cell = tableview.dequeuereusablecellwithidentifier("cellid") as? mycell     if cell != nil {          cell = mycell(style: .default, reuseidentifier: "cellid")     }      let convertedframe = view.convertrect(cell!.mybutton.frame, fromview: cell)      return cell! } 

it gives me current frame of button in own coordinate system (0.0, 0.0, 44.0, 44.0)

any clues on correct usage of method?

it matter of calling before cell placed in view hierarchy. rmaddy pointing out.