如何从iOS Swift Codable的API响应中通知或打印模型类上缺少的键？

Question

我从API收到一个JSON响应，如下所示：

先前的JSON响应：

[
  {
    "EmployeeId": 711,
    "FirstName": "Steve",
    "LastName": "Jobs"
  },
  {
    "EmployeeId": 714,
    "FirstName": "John",
    "LastName": "Doe"
  }
]

和相同的模型类具有以下代码

class EmployeeModel: Codable {

    let EmployeeId: Int?
    let FirstName: String?
    let LastName: String?
}

与Swift Codable解析工作正常

do {
    let decodedResponse = try JSONDecoder().decode([EmployeeModel].self, from: response.rawData())
    print(decodedResponse)

} catch let jsonErr {
    print(jsonErr.localizedDescription)
}

但是现在

最新的JSON响应

从API更改，并添加了一个MiddleName键作为响应，请参见以下屏幕截图，并且它与Swift Codable代码也可以正常工作。

但是，如何从iOS Swift 5的API的JSON响应中获得通知或打印MiddleName密钥的信息呢？

更新问题

根据@ CZ54在下面提供的答案，解决方案可以正常工作，但无法检查是否缺少另一个派生类。例如：

// MARK:- LoginModel
class LoginModel: Codable {

    let token: String?
    let currentUser: CurrentUser?
}

// MARK:- CurrentUser
class CurrentUser: Codable {

    let UserName: String?
    let EmployeeId: Int?
    let EmployeeName: String?
    let CompanyName: String?
}

Answer 1

您可以执行以下操作：

let json = """
    {
        "name" : "Jobs",
        "middleName" : "Bob"
    }
"""


class User: Decodable {
    let name: String
}
extension JSONDecoder {
    func decodeAndCheck<T>(_ type: T.Type, from data: Data) throws -> T where T : Decodable  {
       let result = try self.decode(type, from: data)

        if let json = try? JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions()) as? [String: Any] {
            let mirror = Mirror(reflecting: result)
            let jsonKeys = json.map { return $0.0 }
            let objectKeys = mirror.children.enumerated().map { $0.element.label }

            jsonKeys.forEach { (jsonKey) in
                if !objectKeys.contains(jsonKey) {
                    print("\(jsonKey) is not used yet")
                }
            }
        }
        return result

    }
}

try JSONDecoder().decodeAndCheck(User.self, from: json.data(using: .utf8)!)

//will print "middleName is not use yet"