[英]How do I access this array of structs - Swift
我创建了一个名为“问题”的数组,该数组充满了结构“ QuizQuestion”的实例-基本上,我希望“ nextQuestion”函数从结构(问题)数组中提取下一个问题并将其显示给用户(我了解如何通过标签等显示数据,我只是不知道如何访问它)。
我尝试过调用数组索引,然后再调用实例,但这似乎不起作用。 我也尝试过创建“ QuizQuestion”的实例作为变量,并在“ NextQuestion”函数中使用它的实例,但是我不知道如何从“问题”中自动提取问题。
谢谢
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var questionLabel: UILabel!
@IBOutlet weak var answerLabel: UILabel!
@IBOutlet weak var explanationLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
questionVariable()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
struct QuizQuestion {
let question: String
let answer: Bool
let explanation: String
}
let questions: [QuizQuestion] = [
QuizQuestion(question: "Red is a four letter word", answer: false, explanation: "Red is not a four letter word"),
QuizQuestion(question: "Dog is a three letter word", answer: true, explanation: "Dog is most likely a three letter word"),
QuizQuestion(question: "Cow is a three letter word", answer: true, explanation: "Cow is most likely a three letter word")
]
var nextQuestion = QuizQuestion.self[1]
func questionVariable() {
if nextQuestion.answer == true {
questionLabel.text = nextQuestion.question
explanationLabel.text = nextQuestion.explanation
answerLabel.text = "Correct"
}
}
}
您可以如下定义嵌套函数 (Swift中最简单的闭包形式):
func getNextQuestion() -> (Int) -> QuizQuestion!
{
func incrementor(var index:Int) -> QuizQuestion! {
if index < questions.count && index >= 0 {
return questions[index]
}
else {
return nil
}
}
return incrementor
}
然后您可以访问您的问题列表,如下所示
let nextQuestion = getNextQuestion()
var question_1 = nextQuestion(0)
var question_2 = nextQuestion(1)
var question_3 = nextQuestion(2)
println("1.question text: \(question_1.question)")
println("2.question text: \(question_2.question)")
println("3.question text: \(question_3.question)")
一个简单的函数,用于从数组中检索问题。 声明一个实例变量以保存当前索引。
var currentIndex = 0
func nextQuestion() -> QuizQuestion {
// initialize current question
var currentQuestion: QuizQuestion = QuizQuestion(question: "", answer: false, explanation: "")
if currentIndex < questions.count {
currentQuestion = questions[currentIndex]
}
currentIndex++
return currentQuestion
}
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