Changing UIImage after click - swift

Question

I have 13 images named 1 to 13 in my project. I would like the UIImageView to change from image 1 to 2, then 3, then 4 and so on, at the click of a UIButton.
My current code when the UIButton is clicked:
#IBAction func button(sender: Any) {
cardImage.image = UIImage(named: 1)
}
So I know I need to store the value in a variable and initially set the value to 1. Add 1 to the value every time I click the UIButton. That value needs to be somehow linked to cardImage.Image = UIImage. How can I achieve this?

Answer 1

So create an array of your filenames in your view controller, and an index into that array:
class ViewController: UIViewController {
lazy var filenames: [String] = {
return Array(1...13).map {String($0)}
}()
var filenameIndex = 0
Then write a function to load one of your images and increment the index:
func fetchImage() -> UIImage? {
let result = UIImage(named: filenames[filenameIndex])
filenameIndex = (filenameIndex + 1) % filenames.count
return result
}
(You could also use Yury's approach of managing an integer index and converting that to a filename, but my approach will let you manage cycling through any array of image filenames, whether they are sequential numbers or not.)

Answer 2

You need to store your current image number value in a variable and increase in when the button is pressed.
let imagesCount: Int = 13
var currentImageNumber: Int = 1
#IBAction func didPressButton(sender: Any) {
cardImage.image = UIImage(named: "\(currentImageNumber)")
currentImageNumber += 1
if currentImageNumber > imagesCount {
currentImageNumber = 1
}
}
Or you can use a shorter version without if condition.
let imagesCount: Int = 13
var currentImageNumber: Int = 0
#IBAction func didPressButton(sender: Any) {
cardImage.image = UIImage(named: "\(currentImageNumber + 1)")
currentImageNumber += 1
currentImageNumber %= imagesCount
}