Swift 4 JSONDecoder Complex Data Missing Key - json

Question

I have been struggling with this for over a day now and Im not sure why I keep getting the Missing Key error when I clearly defined the key in my struct. Your help would be really appreciated. Please help clear up my confusion on how to decode nested types in JSON.
I am trying to parse the following JSON response but keep getting the Missing Key error message when I run my app. Below is the message I get back from the service.
Here is the JSON resonse
{
UserInfo = {
ApplicationArea = {
CreationDateTime = "2018-02-11 21:34:40.646000";
MfgCode = PSUN;
Sender = DM;
};
ServiceStatus = {
StatusCode = 0;
StatusDescription = Success;
System = "Product Info";
};
UserInfoDataArea = {
Email = "john#example.com";
Locale = "en_US";
UserId = 3;
UserName = jdoe;
};
};
}
Here is the ERROR
Missing Key: applicationArea
Debug description: No value associated with key applicationArea ("ApplicationArea").
Below is my struct code for getting the request and to decode the response.
struct UserInfo:Codable {
struct ApplicationArea:Codable {
let creationDateTime: String
let mfgCode: String
let sender: String
private enum CodingKeys: String, CodingKey {
case creationDateTime = "CreationDateTime"
case mfgCode = "MfgCode"
case sender = "Sender"
}
}
let applicationArea: ApplicationArea
enum CodingKeys: String, CodingKey {
case applicationArea = "ApplicationArea"
}
}
Code for creating the request
let apiMethod = HTTPMethod.post
Alamofire.request(
loginURL!,
method: apiMethod,
parameters: params,
encoding: URLEncoding.default,
headers: header)
.responseJSON { (response) -> Void in
switch response.result {
case .success:
print(response.result.value)
let result = response.data
do {
let decoder = JSONDecoder()
let userDetails = try decoder.decode(UserInfo.self, from: result!)
print("Response \(userDetails)")
} catch DecodingError.keyNotFound(let key, let context) {
print("Missing Key: \(key)")
print("Debug description: \(context.debugDescription)")
} catch {
print("Error \(error.localizedDescription)")
}
case .failure(let error):
print("Error \(error)")
}
}

Answer 1

You are making a very common mistake: You're ignoring the root object, the outermost dictionary containing the UserInfo key.
Create a Root struct
struct Root: Decodable {
let userInfo : UserInfo
enum CodingKeys: String, CodingKey { case userInfo = "UserInfo" }
}
And decode
let root = try decoder.decode(Root.self, from: result!)
let userDetails = root.userInfo