swift - 使用函数中的两个值

Question

我已经开始使用 Swift 制作一个基本的问答游戏。我编写了一个结构来定义我想要与每个问题相关的内容:

struct Question {
  let question: String
  let answers: [String]
  let correctAnswer: Int
}

该游戏将是一个基本的数学测验，因此将显示随机的数学问题。我编写了一个函数来随机化问题并获取答案:

func questionAnswerBuilder() -> (question: String, answer: String) {
let first: Int = randomNumber()
let second: Int = randomNumber()
let arr = [first,second].sorted(by: >)

let firstAsString = String(arr[0])
let secondAsString = String(arr[1])

let questionString = "\(firstAsString) + \(secondAsString)"
let question = questionString

//Answer:
let answerString = first + second
let answer = String(answerString)

return (question, answer)
}

我已经在 Playground 上测试过了，效果很好。每次它都会创建一个随机数并将其与正确答案一起输出。现在我想在每个问题中使用它......

var questionTest = questionAnswerBuilder()

var questions: [Question] = [
Question(question: questionTest.question, answers: [randomAnswer(), randomAnswer(), questionAnswerBuilder().answer, randomAnswer()], correctAnswer: 2),
Question(question: questionTest.question, answers: [randomAnswer(), randomAnswer(), questionAnswerBuilder().answer, randomAnswer()], correctAnswer: 2)
]

有关信息，randomAnswer()此处不显示功能。它基本上只是一个随机数生成器。

当我将所有这些输入 Xcode 时，我收到以下消息: Cannot use instance member 'questionTest' within property initializer; property initializers run before 'self' is available .

我目前有 questionAnswerBuilder()函数在它自己的 swift 文件中。我尝试将其移至与我的 questions 相同的文件中变量，但我仍然遇到同样的错误。我也尝试过制作 questionTest变量懒惰但这没有什么区别。

请有人指出我错在哪里!

提前致谢!

Answer 1

您无法初始化类顶层相互依赖的属性。

解决方案是延迟初始化问题

lazy var questions: [Question] = {
    return [Question(question: questionTest.question, answers: [randomAnswer(), randomAnswer(), questionAnswerBuilder().answer, randomAnswer()], correctAnswer: 2),
            Question(question: questionTest.question, answers: [randomAnswer(), randomAnswer(), questionAnswerBuilder().answer, randomAnswer()], correctAnswer: 2)]
}()