Pass Variable through View Controllers

Question

I am using xcode swift to create a quiz game, and when the game finished, there will be a score which is revealed. The score is added in the quiz view controller, while the score is going to be shown in the next view controller. I am having trouble trying to bring the variable for the score, to the next view controller. Here is my code for the quiz view controller:


class MathsViewController: UIViewController {
    

    let questions = ["What is the turning point of the graph, y = x^2 + 8x + 6 ?", "What are the x-intercepts of the graph, y = x^2 + 11x + 18 ?", "What is the triganomic ratio used when relating the opposite and adjacent?", "What would be the final form of the equation, 14/x = sin(20) ?", "Which equation, would have the steepest slope?", "If we added every positive whole number, what would the solution be?", "Which of the following is the fibonacci sequnce?", "What are the first 10 digits of pi?", "What is the probability of getting a 6 in all your rolls, when rolling a dice 3 times?", "If the hypostenuse of a triangle is 26cm, and a side edge is of 10cm long. What is the length of the other side?"]
    

    let answers = [["(-4, -10)", "(0,0)", "(-6, -1)"], ["x = -2 or x = -9", "x = 18 or x = 11", "x = 9 or x = 2"], ["tan", "cos", "sin"], ["x = 14/sin(20)", "x = 14sin^-1/20", "x = sin^-1(20)"], ["y = 5x+2", "y = 1/3x+4", "y = x+16"], ["-1/12", "infinity", "0"], ["1,1,2,3,5,8,13", "1,2,3,4,5,6,7", "1,1,2,2,4,8,32"], ["3.1415926535", "3.141533536", "3.1415934435"], ["1/216", "1/36", "1/6"], ["24cm", "28cm", "26cm"]]
    

    //Variables
    var currentQuestion = 0
    var rightAnswerPlacement = 0
    var points = 0;
    

    //Label
    @IBOutlet weak var Label: UILabel!
    

    //Button
    @IBAction func action(_ sender: Any)
    {
        if (sender as AnyObject).tag == Int(rightAnswerPlacement)
        {
            print("RIGHT!")
            points += 1
        }
        else
        {
            print("WRONG!!!")
        }
        

        if (currentQuestion != questions.count)
        {
            newQuestion()
        }
        else
        {
            performSegue(withIdentifier: "showScore", sender: self)
        }
        print(points)
    }
    

    

    override func viewDidLayoutSubviews() {
        newQuestion()
    }
    

    //Function that displays new question
    func newQuestion()
    {
        Label.text = questions[currentQuestion]
        

        rightAnswerPlacement = Int(arc4random_uniform(3)+1)
        

        //Create Button
        var button:UIButton = UIButton()
        

        var x = 1
        

        for i in 1...3
        {
            //Create a button
            button = view.viewWithTag(i) as! UIButton
            

            if (i == Int(rightAnswerPlacement))
            {
                button.setTitle(answers[currentQuestion][0], for: .normal)
            }
            else
            {
                button.setTitle(answers[currentQuestion][x], for: .normal)
                x = 2
            }
        }
        currentQuestion += 1
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

Here is also the pictures of the view controllers in the storyboard:

Quiz view controller

Score view controller

I’m just learning Swift, but I think you have to add a prepareForSegue() function that takes your score variable from the current view controller and passes it to the next view controller — Ethan, Oct 20 '20 at 10:12
Possible duplicate of: [Passing Data between View Controllers](https://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) — TylerP, Oct 20 '20 at 10:31
There are a lot of bad practices: 1) Use a custom struct instead of multiple arrays for questions and answers 2) Declare the `sender` in `action` as `UIButton` to get rid of the ugly `as AnyObject` cast 3) Creating an `Int` from an `Int` is redundant (`if sender.tag == rightAnswerPlacement`) 4) name variables always with starting lowercase letter. 5) `arc4random_uniform` is outdated, use native `Int.random(in:)` 6) This is Swift: No parentheses around an `if` expression and no trailing semicolons. — vadian, Oct 20 '20 at 10:53

score 1 · Answer 1 · answered Oct 20 '20 at 10:29

1

you can pass the value using prepareForSegue as follows:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "showScore" {
            if let resultController = segue.destination as? ScoreViewController {
                resultController.score = points
            }
        }
 }

answered Oct 20 '20 at 10:29

Anjali Aggarwal

611
4
8

Where should I add this? – Photosynthesis Oct 20 '20 at 10:39
In MathsViewController (from where you plan to go to ScoreViewController) class. – Anjali Aggarwal Oct 20 '20 at 10:44
It says there is a unresolved identifier, 'segue'? Sorry to bother you. – Photosynthesis Oct 20 '20 at 10:48
Is the problem resolved? – Anjali Aggarwal Oct 20 '20 at 10:59
Sorry what do you mean by that? When I typed your code, word for word, the line, 'if segue.identifier' has an error, which says, "unresolved identifier, 'segue'" – Photosynthesis Oct 20 '20 at 11:12
Please share how you added the code with a screenshot as for me it is working – Anjali Aggarwal Oct 20 '20 at 12:07
This is a google drive with all the pictures, https://drive.google.com/drive/folders/14_7OA6vS7bbhoLvKOOvJx8OfTLNJm9ss?usp=sharing – Photosynthesis Oct 20 '20 at 12:14
You seem to have placed code out of the class. Please add the code within your class. – Anjali Aggarwal Oct 20 '20 at 12:18
I have placed it in the class, but there is still the same issue – Photosynthesis Oct 20 '20 at 12:19

Pass Variable through View Controllers

1 Answers1