Hi, I have an array of all possible questions (allPossibleQuestions) and I select random questions to create an array of questions for the user to answer (questionTable). After randomly selecting a question to add to the question array, I would like to remove it from the list of all possible questions to avoid asking dupliate questions. I'm aware of ".firstIndex(of:)" but that doesn't appear to work with my array of Question objects. Any thoughts/advice would be much appreciated. Cheers, Scott.

struct Question {
    var firstNumber = 0
    var secondNumber = 0
    var questionString: String {
        return "\(firstNumber) x \(secondNumber)"
    }
    var answer: Int {
        return firstNumber * secondNumber
    }
}   

struct ContentView: View {

...

   func newGame(for timesTable: Int) {
        //reset game state
        questionTable.removeAll()

        let timesTables = [1,2]

        var allPossibleQuestions = [Question]()

        //build table of all possible questions
        for table in timesTables {

            for secondNumber in 1...12 {
                let question = Question(firstNumber: table, secondNumber: secondNumber)
                allPossibleQuestions.append(question)

            }

        }

        // build the table of random questions
        for _ in 1...numberOfQuestions {

            // randomly select the questions to add to the questions array
            if let randomQuestion = allPossibleQuestions.randomElement() {
                questionTable.append(randomQuestion)
            } 

            // once the question has been used, remove it from the array asking duplicate questions.
            if let indexNumb = allPossibleQuestions.firstIndex(of: randomQuestion) {
                allPossibleQuestions.remove(at: indexNumb)
            }
        }

.shuffle() works perfectly - thanks @NigelGee for your help and the really quick response! 🙂