如何声明具有函数外部的结构数组的变量

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

你可以声明currentQuestion作为可选功能外：

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

虽然你可以做到这一点，更好的方法是使你的函数回报随机问题，像这样的：

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

现在您可以使用该函数来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)