ios - 从 JSON 加载信息

我的 JSON 文件中有 3 行(问题)。当应用程序启动时，我想从 JSON 加载信息。在 title 我想从 question.number 加载信息，在 textLabel.text 我想从 question.text< 加载信息，在 showAnswerLabel.text 我想从 question.answer 加载信息。当我从 question.answer 中写入 textField 正确答案并按下键盘上的完成按钮时，我想看到 print("right")在控制台和我的设备中，我想查看下一个问题。但我有一个问题。当应用程序启动时，我从 JSON 加载第一行 ({"number": "1", "text": "1", "answer": "1"},)。在我的 showAnswerLabel.text answer = 1 中。但是当我在 textField 中编写 1 并按下完成按钮时，我没有在控制台中得到 print("right") 。但是如果我从第二行写 answer = 2 ({"number": "2", "text": "2", "answer": "2"},) 从 textField 中的 JSON 并按完成按钮，我在控制台中得到 print("right")。但正确答案应该是 showAnswerLabel.text 中的数字，即 1。如何解决？

我的新代码:

{
    "questions" : [{"number": "1", "text": "1", "answer": "1"},
                   {"number": "2", "text": "2", "answer": "2"},
                   {"number": "3", "text": "3", "answer": "3"}]
}

struct Root : Decodable {
    let questions : [Question]
}

struct Question : Decodable {
    let number, text, answer : String
}

class ViewController: UIViewController, UITextFieldDelegate {

var counter = 0
var questions = [Question]()
@IBOutlet var textLabel: UILabel!
@IBOutlet var showAnswerLabel: UILabel!
@IBOutlet weak var textField: UITextField!

override func viewDidLoad() {
        super.viewDidLoad()

        let url = Bundle.main.url(forResource: "0", withExtension: "json")!
        let data = try! Data(contentsOf: url)
        let result = try! JSONDecoder().decode(Root.self, from: data)
        self.questions = result.questions

        textField.delegate = self
        textField.returnKeyType = .done
        _ = textFieldShouldReturn(textField)

    }

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()

        let question = questions[counter]
        title = question.number
        textLabel.text = question.text
        showAnswerLabel.text = question.answer
        counter = (counter + 1) % questions.count

        if textField.text == question.answer {
            print("right")

        }

        return true
    }

---

Best Answer-推荐答案

从 textFieldShouldReturn 中提取 UI 更新并绑定(bind)到 counter 的更改的可能修复:

class ViewController: UIViewController, UITextFieldDelegate 
{
    var questions = [Question]()
    @IBOutlet var textLabel: UILabel!
    @IBOutlet var showAnswerLabel: UILabel!
    @IBOutlet weak var textField: UITextField!

    var counter: Int = -1 {
       didSet {
           guard counter >= 0, counter < questions.count else { fatalError() }       
           let question = questions[counter] 
           updateUI(with: question)
       }
    }

    override func viewDidLoad() 
    {
        super.viewDidLoad()

        let url = Bundle.main.url(forResource: "0", withExtension: "json")!
        let data = try! Data(contentsOf: url)
        let result = try! JSONDecoder().decode(Root.self, from: data)
        self.questions = result.questions
        textField.delegate = self
        textField.returnKeyType = .done

        counter = 0 // will trigger `updateUI(with: questions[0])`
    }

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()

        let question = questions[counter]        
        if textField.text == question.answer {
            print("right")
            // increment counter only answer is right
            // will trigger an UI update
            counter = (counter + 1) % questions.count 
        }

        return true
    }

    func updateUI(with question: Question) {
        title = question.number
        textLabel.text = question.text
        showAnswerLabel.text = question.answer
    }
}

我不会完全这样做，但你明白了。

关于ios - 从 JSON 加载信息，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48183879/