ios - 如何在函数外声明具有结构数组的变量

Question

我需要在 randomQuestionGenerator 函数之外使用 currentQuestion 变量。预先声明它的正确语法是什么？

struct Questions {
    var Question: String
    var answer: Int
    var answers: [String]
}

class GameScreen: UIViewController {

var correctAnswer = 0
var fullQuestions: [Questions] = []

func RandomQuestionGenerator(){
    let randomQuestion = 
Int(arc4random_uniform(UInt32(fullQuestions.count)))
    var currentQuestion = fullQuestions[randomQuestion]
    correctAnswer = currentQuestion.answer

Answer 1

您可以将 currentQuestion 声明为函数外的可选:

var currentQuestion : Questions? = nil
func RandomQuestionGenerator() {
    let randomQuestion = Int(arc4random_uniform(UInt32(fullQuestions.count)))
    currentQuestion = fullQuestions[randomQuestion]
    correctAnswer = currentQuestion.answer
}

尽管您可以这样做，但更好的方法是让您的函数返回随机问题，如下所示:

func RandomQuestionGenerator() -> Questions {
    let randomQuestion = Int(arc4random_uniform(UInt32(fullQuestions.count)))
    return fullQuestions[randomQuestion]
}

现在您可以使用该函数检索下一个随机问题，并根据需要获取其字段:

let nextQuestion = RandomQuestionGenerator()
print(nextQuestion.Question)
print(nextQuestion.answers)