Question

这是我的数组的struct Question { let imgName: String let questionText: String let options: [String] let correctAns: Int var wrongAns: Int var isAnswered: Bool } var questionsArray = [Question]()：

let que1 = Question(imgName: "img1", questionText: "What is 2 x 2 ?", options: ["2", "4", "8", "6"], correctAns: 1, wrongAns: -1, isAnswered: false)
let que2 = Question(imgName: "img2", questionText: "What is 4 + 2 ?", options: ["9", "4", "3", "6"], correctAns: 3, wrongAns: -1, isAnswered: false)
questionsArray = [que1, que2]

以下是当前填充数组的方式：

questionsArray

我想将数据放入文本文件中并填充Question(imgName: "img1", questionText: "What is 2 x 2 ?", options: ["2", "4", "8", "6"], correctAns: 1, wrongAns: -1, isAnswered: false) Question(imgName: "img2", questionText: "What is 4 + 2 ?", options: ["9", "4", "3", "6"], correctAns: 3, wrongAns: -1, isAnswered: false)。所以我创建了一个文件data.txt并将其放入bundle中。以下是data.txt的内容。每个问题都用一个新行分隔。

var arrayOfStrings: [String]?

do {
    if let path = Bundle.main.path(forResource: "data", ofType: "txt") {
        let data = try String(contentsOfFile:path, encoding: String.Encoding.utf8)
        arrayOfStrings = data.components(separatedBy: "\n")
        questionsArray = arrayOfStrings
    }
} catch let err as NSError {
    print(err)
}

我尝试使用这种方法：

Cannot assign value of type '[String]?' to type '[Question]'

但是，我收到了questionsArray = arrayOfStrings行的错误{{1}}。

如何解决这个问题？

Answer 1

这是一个更好的数据管理快速教程。它广泛用于您的代码。

创建一个新的Blank Playground，平台 macOS （重要！）。你可以让游乐场增加更多问题。

粘贴此代码，它会在桌面上创建一个JSON文件questions.json

struct Question : Encodable {
    let imgName: String
    let questionText: String
    let options: [String]
    let correctAns: Int
    var wrongAns: Int
    var isAnswered: Bool
}

let que1 = Question(imgName: "img1", questionText: "What is 2 x 2 ?", options: ["2", "4", "8", "6"], correctAns: 1, wrongAns: -1, isAnswered: false)
let que2 = Question(imgName: "img2", questionText: "What is 4 + 2 ?", options: ["9", "4", "3", "6"], correctAns: 3, wrongAns: -1, isAnswered: false)
let questionsArray = [que1, que2]

do {
    let jsonData = try JSONEncoder().encode(questionsArray)
    let url = URL(fileURLWithPath: NSHomeDirectory()).appendingPathComponent("Desktop/questions.json")
    try jsonData.write(to: url)
} catch {
    print(error)
}

将文件从桌面拖到项目导航器中。确保选中Copy if needed。

在项目中使用此代码

struct Question : Decodable {
    let imgName: String
    let questionText: String
    let options: [String]
    let correctAns: Int
    var wrongAns: Int
    var isAnswered: Bool
}

var questionsArray = [Question]()


let url = Bundle.main.url(forResource: "questions", withExtension: "json")!
let data = try! Data(contentsOf: url)
questionsArray = try! JSONDecoder().decode([Question].self, from: data)

Answer 2

将数据保存在文件中是个好主意。但是在txt的格式中，特别是在这种格式下，下面绝对不是一个好主意：

Question(imgName: "img1", questionText: "What is 2 x 2 ?", options: ["2", "4", "8", "6"], correctAns: 1, wrongAns: -1, isAnswered: false)

你应该使用非常适合这种情况的json格式。您将数据保存到file.json。

怎么做？将Codable协议添加到struct问题：

struct Question: Codable {
    let imgName: String
    let questionText: String
    let options: [String]
    let correctAns: Int
    var wrongAns: Int
    var isAnswered: Bool
}

然后编码数据：

do {
    let encodedData = try JSONEncoder().encode(questionsArray)
    // Write encoded data to file
} catch let err {
    print(err)
}

当您想要检索数据时：

let data = Data(contentsOf: url)
do {
    let decodedData = try JSONDecoder().decode([Question].self, from: data)
} catch let err {
    // Failed to decode data
    print(err)
}

将文本文件加载到数组结构中

2 个答案: