ios - 如何遍历字典，通过快速按下按钮加载下一个项目

Question

我正在制作一个应用程序，它会提出一系列问题，并在回答"is"或“否”时给出一个值。我有一个带有问题类型 Collection View 的初始 View Controller 。该 View Controller 将类型信息传递给具有问题布局(图像、标签、按钮)的新 View Controller 。在第二个 View Controller 上，我有一个 switch/case 语句来为传入的类型(通过 questionTypeReceived)提供正确的字典结果，从而正确填充初始 View 。一旦您回答了问题(简单的是或否)，我想更新下一个问题。有什么建议可以完成这项工作吗？

额外信息:我重构了 View Controller (此处称为辅助 VC)的问题，因为我最初认为我想重用它，而不仅仅是重新加载它。所有方面都有效除了下一个问题的重新加载...是的，那是因为我没有代码可以做到这一点。我一直在不同的地方尝试不同的 for 循环，但不断出现错误，所以我返回到当前设置，因为没有错误

初始风险投资

    let names = [ "Work", "School", "Family", "Friends", "Random" ]

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        questionType = names[indexPath.row] as String
        let storyboard:UIStoryboard = UIStoryboard(name: "questions", bundle: nil)
        let questionsVC = storyboard.instantiateViewController(withIdentifier: "questionsViewController") as! questionsViewController
        questionsVC.questionTypeReceived = questionType
        self.navigationController?.pushViewController(questionsVC, animated: true)
        performSegue(withIdentifier: "question_segue", sender: questionType)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        guard let dest = segue.destination as? questionsViewController else {
            print("Can't perform downcast")
            return
        }
        dest.questionTypeReceived = questionType
    }

二次风险投资

    var questionTypeReceived:String = String()
    var answerTotalValue:Double = Double()
    var questionNumber:Int = Int()
    var questionBody = ""
    var questionType = ""

    let answerYesValue:Double = Double.random(in: 1...5)
    let answerNoValue:Double = Double.random(in: 0..<3)

        switch questionTypeReceived {

        case "Random":
            questionTypeReceived = "Random"
            questionsImageView.image = UIImage(named: randomImages.randomElement()!)
            let questionNumber = randomQuestions.keys.sorted()
            let questionBody = randomQuestions.values
            for (questionNumber, questionBody) in randomQuestions {
                questionTitleLabel.text = "Question #\(questionNumber)"
                questionsTextLabel.text = questionBody
            }
        default: return
        }

    let randomQuestions: [Int : String] = [
        1: "Did you already agree to attend?",
        2: "Does it cost money to attend?",
        3: "Is it time consuming (4+ hours)?"
    ]

    @IBAction func yesButtonPressed(_ sender: UIButton) {
        answerTotalValue += answerYesValue
        print(answerTotalValue)
        print(questionTypeReceived)
    }

Answer 1

关于如何处理属性和局部变量似乎有些困惑，例如，您有 1 个属性和 2 个名为 questionNumber 的局部变量，并且在我看来您也在迭代整个字典你只想要一个问题。

摆脱这种情况的一种方法和一种解决方案也适用于其他原因，例如不在您的 Controller 类中执行所有操作并分离职责，是将问题和它们的处理移动到一个单独的结构或类中。

让我们创建一个 Questions 结构来保存问题，跟踪已提出的问题并可以提供下一个要问的问题。

struct Questions {
    private randomQuestions: [Int : String] = [
        1: "Did you already agree to attend?",
        2: "Does it cost money to attend?",
        3: "Is it time consuming (4+ hours)?"
    ]

    private var questionIndex = 0

    mutating func nextQuestion() -> (number: Int, question: String?) {
        questionIndex += 1
        return (questionIndex, randomQuestions[questionIndex])
    }
}

注意返回元组中字符串的问号，如果索引不存在问题 (questionIndex > 3)，则返回的问题将为 nil

然后你可以像这样在你的代码中使用它，首先在你的VC中将它声明为一个属性

var questions = Questions()

然后在得到问题的时候

switch questionTypeReceived {
case "Random":
    questionsImageView.image = UIImage(named: randomImages.randomElement()!)
    let nextQuestion = question.nextQuestion()
    if let question = nextQuestion.question {
        questionTitleLabel.text = "Question #\(nextQuestion.number)"
        questionsTextLabel.text = question
    } else {
       // no more questions to ask, this needs to be handled
    }
default: return
}

因此编写新结构需要多做一些工作，但您在 VC 中的代码变得更简单并且不再需要许多属性和变量。