在 Swift 中解码 json 对象

Question

我有一个 json 文件并读取它并按如下方式对其进行解码。 我的 json 文件如下所示，A 和 B 代表 struct 对象。我想知道有没有更好更有效的方法来解码这种类型的json？

[ 
 [
   {"id": "152478", "age": "20"},{"character": "king", "isDead":"no", "canMove" :"yes"}
 ],
 [
  {"id": "887541", "age": "22"},{"character": "lion", "isDead":"no", "canMove" :"yes"}
 ]
]

解码如下：

    let url = Bundle.main.url(forResource: "mypew", withExtension: "json")!
        do {

        let jsonData = try Data(contentsOf: url)

         // B -> json[0][0], [1][0]
         // A -> json[0][1], [0][1]

        response = try JSONSerialization.jsonObject(with: jsonData) as! [[[String: Any]]]
        for i in 0..<response.count
        {
            for j in 0..<response[i].count
            {
                if j == 0
                {
                    let jsonDat = (try? JSONSerialization.data(withJSONObject:response[i][j]))!
                    let bElement = try JSONDecoder().decode(B.self, from: jsonDat)
                    self.bArray.append(bElement)
                }
                else if j == 1
                {
                    let jsonDatt = (try? JSONSerialization.data(withJSONObject:response[i][j]))!
                    let aElement = try JSONDecoder().decode(A.self, from: jsonDatt)
                    self.aArray.append(aElement)
                }
            }
        }

Answer 1

首先，使两个对象（我们称它们为A 和B）符合Decodable：

struct A: Decodable {
    var id, age: String
}

struct B: Decodable {
    var character, isDead, canMove: String
}

然后，如果您的 A 和 B 对的结构始终相同，即始终为 [A, B]，那么您可以将这对解码为自己的对象。我们称该对象为ABPair：

struct ABPair: Decodable {
  let a: A
  let b: B

  init(from decoder: Decoder) throws {
    var container = try decoder.unkeyedContainer()

    guard let a = try? container.decode(A.self), 
          let b = try? container.decode(B.self) 
      else {
        // throw since we didn't find A first, followed by B
        throw DecodingError.dataCorruptedError(in: container, debugDescription: "error")
      }

    self.a = a
    self.b = b
  }
}

您可以按如下方式解码对数组：

let decoder = JSONDecoder()
let pairs = try? decoder.decode([ABPair].self, from: jsonData)

print(pairs[1].b.character) // lion

Answer 2

首先，您需要为模型创建一个Codable 结构。然后从数据而不是 JSON 对象中解码模型。这里是代码，

型号：

struct Model: Codable {
    let id, age, character, isDead, canMove: String?
}

解码：

let url = Bundle.main.url(forResource: "mypew", withExtension: "json")!
do {
    let jsonData = try Data(contentsOf: url)
    let models = try JSONDecoder().decode([[Model]].self, from: jsonData)
    for model in models {
        print(model[0].age, model[1].canMove)
    }
} catch {
    print(error)
}