ios - Get a random unique element from an Array until all elements have been picked in Swift

Question

I have the following array:

var notebookCovers = ["cover1", "cover2", "cover3", "cover4", "cover4", "cover6", "cover7", "cover8", "cover9", "cover10"]

and a UIButton that when it's pressed it generates a new UIImage with one of the elements of the array.

What I need to do is every time the button is tapped to generate random but unique element from the array (without repeating the elements) until they've all been selected and then restart the array again.

So far, I have it getting a random element but it's repeated and I cannot figure out how to it so it gets a unique image every time

func createNewNotebook() {
    let newNotebook = Notebook()
    let randomInt = randomNumber()
    newNotebook.coverImageString = notebookCovers[randomInt]
    notebooks.insert(newNotebook, at: 0)
    collectionView.reloadData()
}

func randomNumber() -> Int {
    var previousNumber = arc4random_uniform(UInt32(notebookCovers.count))   
    var randomNumber = arc4random_uniform(UInt32(notebookCovers.count - 1)) 
    notebookCovers.shuffle()
    if randomNumber == previousNumber {
        randomNumber = UInt32(notebookCovers.count - 1)
    }
    previousNumber = randomNumber
    return Int(randomNumber)
}

Answer 1

Set is a collection type that holds unique elements. Converting your notebooks array to Set also lets you take advantage of its randomElement function

var aSet = Set(notebooks)

let element = aSet.randomElement()
aSet.remove(element)