ios - Variable is nil at launch but I want it to be 0 swift -

i have function shows position (moved) of scrollview. @ launch position nil changes move. when go page 1 position 0. can't change launch number not nil item scrolls scales show page position (it doesn't matter if starts 0 or 1 long not nil , goes incrementally) in advance assistance.

var screenpage: int? var screenpos: int? var screenplacefinal: int!  func walkthroughdidscroll(position: cgfloat, offset: cgfloat) {        // getting page number scroll position. first page loads nil want zero.         // position when starts nil want 0       if let screenpage = screenpage {       screenplacefinal = int(((position / view.bounds.size.width) + 1) - 1)        } else {         //show alert ot else         self.screenplacefinal = 0       } 

can initialize screenpos 0? no optional required.

var screenpos: int = 0 

it start 0 , can never nil, because it's not optional.