How to randomize the questions in my quiz app?

Using Swift
1

Hi!

I'm making one of my first apps, a kind of quiz.

The structure of the questions looks like this:

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

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

How can I make the questions appear in a random order? Would it be necessary to change the structure of the questions and answers?

2

assuming you have your questions in an array, you can use the shuffled method to get a new array with the contents shuffled, or a shuffle method to shuffle it in place (remember to make it a var instead of let if you want to shuffle in place).

let allQuestions = [
    Question(text: "Life, the Universe and Everything", answers: [
        Answer(text: "42", correct: true),
        Answer(text: "What?", correct: false),
    ]),
    Question(text: "Monoid in the category of endofunctors", answers: [
        Answer(text: "Tuple", correct: false),
        Answer(text: "Monad", correct: true),
    ]),
]

let questionsInRandomOrder = allQuestions.shuffled()
3

@cukr Thank you!

4

Assuming you have some huge array with all of your questions, and you want to get a small number of random elements without duplicates, I would do something like this:

let questionDatabase: [Question] = ...
let questionsPerQuiz = 10

// Select some random indexes, without duplicates.
var selectedQuestionIndexes: Set<Int> = []
while selectedQuestionIndexes.count < questionsPerQuiz {
  selectedQuestionIndexes.insert(questionDatabase.indices.randomElement())
}

// Get the question from each selected index.
// Shuffle again because they are returned in hash-table order.
var quiz: [Question] = selectedQuestionIndexes.lazy.map { idx in 
  questionDatabase[idx] 
}.shuffled()

This allows you to avoid copying and shuffling the entire database when you only want a few items.

That being said, pure randomness might not actually make the most fun quiz; good question selection can make a big difference. There's often some level of structure behind it - like maybe having separate easy/medium/hard question pools, and mixing them a little (so maybe there's a 5% chance of a hard question in medium mode), or having separate categories so you can control how often particular topics appear (randomness could give you 10 geography questions in a row). So try things out!

5

@Karl Thank you!

6

I think there is a mistake here, so that the questions are not shuffled. What should I change?

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


private func ConfiqureUI(question: Question){
    label.text = question.text
    CurrentQuestion = question
    table.reloadData()
}

I have about 400 questions, so as not to make it boring and lengthy, I would love it if only 20, 50 or 100 random questions are shown in random order. How can I do this?