Changing the image of a button based on control state - ios

Question

I am trying to change the image of a button when clicked, they are stars like a rating system. when clicked the image remains the same and does not change when clicked. I set the default image in story board.
class DetailViewController: UIViewController {
#IBOutlet weak var detailTitleViewLbl: UILabel!
#IBOutlet weak var detailDescription: UILabel!
#IBOutlet weak var yearLabel: UILabel!
#IBOutlet weak var star1: UIButton!
#IBOutlet weak var star2: UIButton!
#IBOutlet weak var star3: UIButton!
#IBOutlet weak var star4: UIButton!
#IBOutlet weak var star5: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
#IBAction func star1Pressed() {
star1.setImage(#imageLiteral(resourceName: "favorite (1).png"), for: UIControlState.selected)
}
func star2Pressed() {}
func star3pressed() {}
func star4pressed() {}
}

Answer 1

A button doesn't change to the selected state when clicked. You need to write code that sets the button's selected flag to true when it's clicked.
Note that you can connect more than one IBAction to a button, so you could have one action that sets the selected flag to true, and another that does custom "stuff", so you don't have to duplicate the "boilerplate" code to set the selected state in the IBAction of every such button.