With Swift 5
For style = BOLD
label.font = UIFont(name:"HelveticaNeue-Bold", size: 15.0)
For style = Medium
label.font = UIFont(name:"HelveticaNeue-Medium", size: 15.0)
For style = Thin
label.font = UIFont(name:"HelveticaNeue-Thin", size: 15.0)