A few minor problems withy quiz app

Using Swift
#1

Hi! My first app, quiz app, is almost ready. I just have a few minor problems.

  1. I can't set the duration of the quiz via buttons (how many questions, I mean). How can I solve this problem? Some code:

    ViewController.swift
    var numberOfQuestions = Int()

    // Buttons
    @IBAction func Vragen20( _ sender: Any ) {

    let vc = storyboard?.instantiateViewController(identifier: "game") as ! GameViewController

    vc.modalPresentationStyle = .fullScreen

    present(vc, animated: true )

numberOfQuestions = 20
}

@IBAction func Vragen50( _ sender: Any ) {

let vc = storyboard?.instantiateViewController(identifier: "game") as ! GameViewController

vc.modalPresentationStyle = .fullScreen

present(vc, animated: true )

numberOfQuestions = 50
}

@IBAction func Vragen100( _ sender: Any ) {

let vc = storyboard?.instantiateViewController(identifier: "game") as ! GameViewController

vc.modalPresentationStyle = .fullScreen

present(vc, animated: true )

numberOfQuestions = 100

}

GameViewController.swift
// Here I need the variable numberOfQuestions

if let index = allQuestions.firstIndex(where: { $0.text == question.text }) {
if Progress < 100 {
// Next question
let NextQuestion = allQuestions.randomElement()
print("(NextQuestion!.text)")
CurrentQuestion = nil
ConfiqureUI(question:NextQuestion!)
Progress += 1
updateLabel()
}
else {
let vc = storyboard?.instantiateViewController(identifier: "end") as! ViewController
vc.modalPresentationStyle = .fullScreen
present(vc, animated: true)
}
}

  1. How can I make it so that the same question never appears twice? (I have enough questions to do that) Some code:

struct Question {
let text: String
let answers: [Answer]
}

struct Answer {
let text: String
let correct: Bool
}

override func viewDidLoad() {
super.viewDidLoad()
table.delegate = self
table.dataSource = self
updateLabel()
ConfiqureUI(question: allQuestions.randomElement()!)
}

Hopefully someone can help me!