swift - Fatal error , can't unwrap optional none -

this simple problem , can't solve , have following full code

  var numberoftimer:int = 0    func increment(){          numberoftimer = numberoftimer + 1 //error here,breakpoint,no error message      if numberoftimer>4{         falafel1.center = cgpointmake(200, 100)        }   }    @iboutlet var fryer:uiimageview @iboutlet var order : uilabel var numberofflafel:uint32!  init(nibname nibnameornil: string?, bundle nibbundleornil: nsbundle?) {     super.init(nibname: nibnameornil, bundle: nibbundleornil)     // custom initialization }  override func viewdidload() {     super.viewdidload()     numberofflafel = arc4random()%11     if numberofflafel<2{         order.text = "make \(numberofflafel) falafel"     }     order.text = "make \(numberofflafel) falafels"         }  init(coder adecoder: nscoder!) {     super.init(coder: adecoder) }   override func touchesmoved(touches: nsset!, withevent event: uievent!) {     let t = touches.anyobject() uitouch      if t.view == falafel1{         let p = t.locationinview(self.view)          falafel1.center = p             if cgrectintersectsrect(falafel1.frame, fryer.frame){             falafel1.center = cgpointmake(385, 192)             nstimer.scheduledtimerwithtimeinterval(1 , target: self, selector: "increment", userinfo: nil, repeats: true)          }          } 

this gives me run time error saying can't unwrap optional none , because i'm accessing doesn't have value , in case , how can solve problem

var num: int? 

declares optional variable, automatically initialized nil (aka optional none), indicating "missing" value. therefore

num = num! + 1 

crashes @ runtime, because no value has been assigned variable.

using optional seems not necessary in case, should declare as

var num: int = 0 // integer variable initial value 0 

and remove "unwrapping" operator ! in method:

func function() {     num = num + 1 // or simply: ++num     if num > 5 {         // ...     } }