迅捷4-json解碼具有樹結構的對象

Question

我想解碼我的用戶json對象，但是在解碼上級對象時遇到了困難。 上級對象只是站在該用戶上方的另一個用戶。 結構看起來像這樣

   {
       "id": 3,
       "username": "a",
       "email": "a@abc.com",
       "userFunction": "4",
       "password": "****",
       "superior": {
           "id": 2,
           "username": "b",
           "email": "b@abc.com",
           "userFunction": "3",
           "password": "****",
           "superior": {
                "id": 1,
                "username": "c",
                "email": "c@abc.com",
                "userFunction": "1",
                "password": "****",
                "superior": null,
            },
        },
   }

   struct UserStructure: Decodable {
       var id: Int64?
       var username: String?
       var email: String?
       var userFunction: UserFunctionStructure?
       var password: String?
       var superior: UserStructure?
   }

   func fetchUser(username: String){
        let urlString = "http://localhost:8080/rest/user/" + username
        let url = URL(string: urlString)!    
        URLSession.shared.dataTask(with: url) { (data, response, error) -> Void in
            if error != nil {
                print(error!)
                return
            }
            guard let data = data else {
                return
            }
            do {
                let user = try JSONDecoder().decode(UserStructure.self, from: data)
                print(user)
            } catch let err {
                print(err)
            }
        }.resume()
    }

當我將上級類型設置為“ UserStructure？”時 我收到錯誤“值類型'UserStructure”不能具有遞歸包含它的存儲屬性。 我曾考慮過創建SuperiorStructure，但接下來我將遇到同樣的問題。

Answer 1

就像編譯器錯誤消息所說的那樣，結構不能具有包含其自身實例的屬性。 在這種情況下使用class ：

class UserStructure: Decodable {
   var id: Int64?
   var username: String?
   var email: String?
   var userFunction: UserFunctionStructure?
   var password: String?
   var superior: UserStructure?
}