ios - setting destinationviewcontroller's label's text in prepareForSegue throws error: unexpectedly found nil while unwrapping Optional value -

i sure string not nil , label exists, trying find out why text in label nil. other members of destinationviewcontroller getting set correctly , add line set label program crashes.

// mark segue override func prepareforsegue(segue: uistoryboardsegue, sender: anyobject?) {     // reference destination view controller     var detailvc = segue.destinationviewcontroller as! detailviewcontroller     var detailimages: array<uiimage> = []     detailimages.append(uiimage(named: "pup.jpg")!)     detailimages.append(uiimage(named: "dog.png")!)     // set property selected location when view     // detail view controller loads, can access property feeditem obj     detailvc.selectedlocation = _selectedlocation;     println(_str!)     detailvc.mylabel.text = "hello" } 

this because outlet mylabel not set in prepareforsegue, nil. try below approach instead,

create string var in detailviewcontroller like,

var labeltext: string? 

in prepareforsegue

override func prepareforsegue(segue: uistoryboardsegue, sender: anyobject?) {     // reference destination view controller     var detailvc = segue.destinationviewcontroller as! detailviewcontroller     var detailimages: array<uiimage> = []     detailimages.append(uiimage(named: "pup.jpg")!)     detailimages.append(uiimage(named: "dog.png")!)     // set property selected location when view     // detail view controller loads, can access property feeditem obj     detailvc.selectedlocation = _selectedlocation;     println(_str!)     detailvc.labeltext = "hello" } 

and in viewdidload of detailviewcontroller

override func viewdidload() {     super.viewdidload()      self.mylabel.text = labeltext     // additional setup after loading view. }