Wrong way of changing the image in UIButton

UIButton_selected_wrongway.swift

func myButtonTapped(){
  if myButton.isSelected == true {
    myButton.isSelected = false
    myButton.setImage(UIImage(named : "unselectedImage"), forState: UIControlState.Normal)
  }else {
    myButton.isSelected = true
    myButton.setImage(UIImage(named : "selectedImage"), forState: UIControlState.Normal)
  }
}