keeping two arrays in sync? - ios

Question

I am currently trying to keep my two arrays in sync. One question label and a one text label..
For my question label, I used arc4Random to pick a random question from my array. However, in order to set the label just above it in the UI, I need it to match my other array.. (titleQuestions)
How do I pull out the titleQuestion by using the arc4random number I generate from the questions array..
Sorry in advance, I am relatively new to Swift and still learning.. first year..
//just vars to get data from my two models(i.e two arrays)
var questionArray = DataModel()
var tArray = TitleLabel()
// this here is questions for the lower UI label. random No generate here!
func questions() {
let questions = questionArray.questions
let randomQuestions = questions.index(questions.startIndex , offsetBy : questions.count.arc4random)
questionLabel.text = questions[randomQuestions]
}
// the questions marks is because I dont know what to index here because I want this number but cant seem to get it!
func titles() {
let titlesArray = tArray.titleQuestions
titleLabel.text = titlesArray[?????]
}
// When this button is pressed both UIlabel will be updated with a random question and the associated title
#IBAction func questionsButton(_ sender: UIButton) {
questions()
titles()
}
I understand this could might be a stupid question but I have wasted a better part of a week trying to work this out.. any help is encouraged! thought about using a closure to take the questions function but really dont know how to implement it..

Answer 1

Welcome to SO. this is a trivial problem, and one you should really work out on your own, but it sounds like you're stuck, so I'll take pity on you.
At the simplest, take the code that generates a random number out of the line that fetches an item, and instead assign the random number to a temp variable, and set both labels from a single function:
func questionsAndTitles() {
let randomInt = Int(arc4random_uniform(Uint32(questions.count)))
let questions = questionArray.questions
questionLabel.text = questions[randomInt]
let titlesArray = tArray.titleQuestions
titleLabel.text = titlesArray[randomInt]
}
(Assuming questions is of type Array, there's no reason to create an Index object in order to fetch an item from the array. Arrays allow integer subscripting.)
However, it might make more sense to create an array of structures that contain both a question and an answer. That way you would fetch an instance of a question-and-answer struct from your array and use it to populate both.
Edit:
If you wanted to create an array of structs it might look like this:
struct QuestionStruct {
let question: String
let possibleAnswers: [String]
let correctAnswerIndex: int
}
var questions: [QuestionStruct] =
[
QuestionStruct(
question: "What is the airspeed velocity of an unladen swallow?",
possibleAnswers: ["3 ft/sec", "2.2 ft/sec", "European or African"],
correctAnswerIndex: 2),
QuestionStruct(
question: "What is Your favorite color?",
possibleAnswers: ["Blue", "Green", "Blue. No, Green! Ieee!"],
correctAnswerIndex: 2)
]
//And then you might use code like this:
let randomIndex = Int(arc4random_uniform(UInt32(questions.count)))
let aQuestion = questions[randomIndex]
let correctAnswerIndex = aQuestion. correctAnswerIndex
questionLabel.text.text = aQuestion.question
correctAnswerLabel.text = aQuestion.possibleAnswers[correctAnswerIndex]

Answer 2

You can store your picked random number in a class variable so it is accessible both from your questions() and titles() methods.
Use a property declared at the class scope :
var lastRandomSeed: Int?
Reuse it in both of your methods :
if let lastRandomSeed = lastRandomSeed {
let randomQuestions = questions.index(questions.startIndex , offsetBy : lastRandomSeed)
lastRandomSeed = nil
} else {
lastRandomSeed = questions.count.arc4random
let randomQuestions = questions.index(questions.startIndex , offsetBy : lastRandomSeed)
}
and :
if let lastRandomSeed = lastRandomSeed {
titleLabel.text = titlesArray[lastRandomSeed]
lastRandomSeed = nil
} else {
lastRandomSeed = questions.count.arc4random
titleLabel.text = titlesArray[lastRandomSeed]
}
This also ensures you can call your methods in both order.
A better approach is to refactor your code, use computed property that will update the view :
var lastRandomSeed: Int = -1 {
didSet {
let questions = questionArray.questions
let randomQuestions = questions.index(questions.startIndex , offsetBy : lastRandomSeed)
let titlesArray = tArray.titleQuestions
questionLabel.text = questions[lastRandomSeed]
titleLabel.text = titlesArray[lastRandomSeed]
}
}
Just write it in your IBAction :
let questions = questionArray.questions
lastRandomSeed = questions.count.arc4random

Answer 3

You had to discipline yourself first. Try to name your variables, functions and even local variables by it's purpose. So at any point you can understand whats this variable/function/Type is used for.
So in you example I can assume that DataModel type is subclass of an array, because you assigning it's instance to variable questionArray. It is not very straightforward, but more or less ok (however better to name it DataArray). But then one who looking at you code can realise that your array not array. It is object that have array of questions in it. So you either had to name it let questionArrayHolder = DataModel() or fill it with questions: let questionArray = DataModel().questions.
But then you assign instance of TitleLabel to variable tArray. t can mean anything, and it definitely doesn't look like array. If you want to create array with single object in it, declare it titleArray = [TitleObjects]
Then you have function question()
It's name naturally suggests that it had to return some questions. But it returns nothing. If you want to generate questions name you function appropriate: func generateQuestions() . But your function do not generate questions, it picking up one question and assigning it to title. So you had name it like func pickupRandomQuestion().
You have lot of opportunities to share soothing between functions. You can declare member variable var selectedQuestion: Int? = 0 and assign your arc4rand number to it before retrieving you question.
You can find index of you question in array, assuming that all questions are unique, questions.index(of: questionLabel.text)
And you can return question number from you function:
func pickupRandomQuestion() -> Int {
let randNumber = questions.count.arc4random // I'm assuming that you have that function, and it works for you as you expect
let randomQuestion = questions.index(questions.startIndex , offsetBy : randNumber)
questionLabel.text = questions[randomQuestion]
return randNumber
}
And then supply it to other function
func pickupTitleForQuestion(at index: Int) {
titleLabel.text = titlesArray[index]
}