Generating Random UIImages that don't repeat - ios

Question

In my app project I am displaying 107 of my images at random, I have set up a for loop that puts all of my images into an array. I then take that array and choose a random Index. That index correlates to a picture and then that picture appears on the screen when the user swipes to the left. My question is that can I make it so my code will not repeat the same index in the array until all of them (or the amount until closing the app) have been chosen at random. Here is my code
class ViewController: UIViewController {
var pictureArray: [String] = []
#IBOutlet weak var quoteImage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
for i in 0...107{
pictureArray.append("quote\(i).jpg")
print(pictureArray)
}
// Do any additional setup after loading the view, typically from a nib.
let swipeRecognizer = UISwipeGestureRecognizer(target: self, action: #selector (changeQuotes))
swipeRecognizer.direction = UISwipeGestureRecognizerDirection.left
self.view.addGestureRecognizer(swipeRecognizer)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override var prefersStatusBarHidden: Bool{
return true
}
#objc func changeQuotes(){
let numberOfImages: UInt32 = 107
let randomIndex = Int(arc4random_uniform(UInt32(pictureArray.count)))
let imageName = "\(pictureArray[randomIndex])"
print(imageName)
quoteImage.image = UIImage(named: imageName)
}
}
Thanks for any help!

Answer 1

Flush your array randomly, then just get the "sorted" image one by one.
extension Sequence {
func randomSorted() -> [Element] {
var result = Array(self)
guard result.count > 1 else { return result }
for (i, k) in zip(result.indices, stride(from: result.count, to: 1, by: -1)) {
let newIndex = Int(arc4random_uniform(UInt32(k)))
if newIndex == i { continue }
result.swapAt(i, newIndex)
}
return result
}
}

Answer 2

You can generate unique random number by managing 2 arrays one contains images that are not yet displayed and one that are already displayed
Make following changes in your code
var pictureArray: [String] = []
var selectedPictureArray: [String] = []
static let TOTAL_IMAGES = 108
#IBOutlet weak var quoteImage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
self.fillPictureArray()
let swipeRecognizer = UISwipeGestureRecognizer(target: self, action: #selector (changeQuotes))
swipeRecognizer.direction = UISwipeGestureRecognizerDirection.left
self.view.addGestureRecognizer(swipeRecognizer)
}
func fillPictureArray() {
self.selectedPictureArray.removeAll()
for i in 0..<ViewController.TOTAL_IMAGES {
pictureArray.append("quote\(i).jpg")
}
print(pictureArray)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override var prefersStatusBarHidden: Bool{
return true
}
func changeQuotes(){
if self.pictureArray.count == 0 {
self.fillPictureArray()
}
var randomIndex = 0
while true {
randomIndex = Int(arc4random_uniform(UInt32(ViewController.TOTAL_IMAGES)))
if self.selectedPictureArray.contains("quote\(randomIndex).jpg") {
continue
}else {
break
}
}
let imageName = "quote\(randomIndex).jpg"
self.selectedPictureArray.append(imageName)
print(imageName)
quoteImage.image = UIImage(named: imageName)
let index = self.pictureArray.index(of: imageName)
self.pictureArray.remove(at: index!)
}
Happy coding :)