如何在iOS Swift中将对象数组转换为Json数组或Json字符串？

Question

我有一个数组，其中有一组对象var quiz_anwers_list = [QuizQu]() “ QuizQu”是一个包含2个变量的类

class QuizQu: Decodable {
    var ques_id: String?
    var their_answer: String?
}

现在有

for i in 0...self.quiz_anwers_list.count-1{

            print(self.quiz_anwers_list[i].ques_id ?? "no val in ques id of \(i)")
            print(self.quiz_anwers_list[i].their_answer ?? "no val in their_ans of \(i)")
        }

这些打印的输出是：

14
correct_answer
15
correct_answer2
16
correct_answer2
17
correct_answer

现在如何将其转换为JsonArray或JSON String？ 我是iOS的新手。

Answer 1

您的类可能应该是一个结构，并且应该符合Encodable而不是Decodable ，如果您打算编码和解码，则可以使用涵盖两种情况的Codable协议。

完成此操作后，只需使用JSONEncoder将其转换为JSON数据，然后即可使用String(bytes: Sequence, encoding: String.Encoding)打印它

struct QuizQu: Codable {
    var ques_id: String?
    var their_answer: String?
}

let questions = [
    QuizQu(ques_id: "1", their_answer: "2"),
    QuizQu(ques_id: "2", their_answer: "2"),
    QuizQu(ques_id: "3", their_answer: "1"),
    QuizQu(ques_id: "4", their_answer: "4"),
    QuizQu(ques_id: "5", their_answer: "3")
]

do {
    let encoded = try JSONEncoder().encode(questions)
    print(String(bytes: encoded, encoding: .utf8))
} catch {
    print(error)
}

输出：

可选（ “[{\\” ques_id \\ “：\\” 1 \\” \\ “their_answer \\”：\\ “2 \\”}，{\\ “ques_id \\”：\\ “2 \\” \\ “their_answer \\”：\\ “2 \\”}，{\\ “ques_id \\”：\\ “3 \\” \\ “their_answer \\”：\\ “1 \\”}，{\\ “ques_id \\”：\\ “4 \\” \\ “their_answer \\” ：\\ “4 \\”}，{\\ “ques_id \\”：\\ “5 \\”，\\ “their_answer \\”：\\ “3 \\”}]“）

注意：输出的String被转义，因此反斜杠

Answer 2

你可以做到

    extension Encodable {
      var dictionary: [String: Any]? {
        guard let data = try? JSONEncoder().encode(self) else { return nil }
        return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
      }
}

let struct = QuizQu(ques_id: 1, their_answer: abc)
let jsonObj = struct.dictionary