使用Swift 4的可解碼協議嵌套JSON服務器響應

Question

我想實現Swift 4的新的可解碼協議，並有一些難以接近它。

這是我的JSON服務器響應：

{ 
    "success": true, 
    "errorCode": 0, 
    "message": "Succcess", 
    "data": { 
    "name": "Logan Howlett", 
    "nickname": "The Wolverine", 
    "image": "http://heroapps.co.il/employee-tests/ios/logan.jpg", 
    "dateOfBirth": 1880, 
    "powers": [ 
     "Adamantium Bones", 
     "Self-Healing", 
     "Adamantium Claws" 
    ], 
    "actorName": "Hugh Jackman", 
    "movies": [ 
     { 
     "name": "X-Men Origins: Wolverine", 
     "year": 2009 
     }, 
     { 
     "name": "The Wolverine", 
     "year": 2013 
     }, 
     { 
     "name": "X-Men: Days of Future Past", 
     "year": 2014 
     }, 
     { 
     "name": "Logan", 
     "year": 2017 
     }, 
    ] 
    } 
} 

什麼是解碼響應data部分的最佳方法？ 另外，如果data突然變爲array而不是對象會發生什麼情況，我如何支持這兩種數據類型？

感謝很多:)

Answer 1

首先你可以創建一個擴展爲一個幫手：

extension Data { 
    func decode <Generic: Codable>() -> Generic? { 
     let decoder = JSONDecoder() 
     let object = try? decoder.decode(Generic.self, from: self) 
     return object 
    } 
} 


extension Dictionary { 
    func decode <Generic: Codable>() -> Generic? { 
     let data = try? JSONSerialization.data(withJSONObject: self, 
               options: JSONSerialization.WritingOptions.prettyPrinted) 
     guard let d = data else { 
      return nil 
     } 
     return d.decode() 
    } 
} 

然後你就可以創建一個協議，以幫助你建立你的對象：

protocol Encode: Codable { 
    init(with dictionary: [String: Any]) 
    init(with data: Data) 
} 

默認執行：

extension Encode { 
    init(with data: Data) { 
     let object: Self? = data.decode() 
     guard let obj = object else { 
      fatalError("fail to init object with \(data)") 
     } 
     self = obj 
    } 

    init(with dictionary: [String: Any]) { 
     let object: Self? = dictionary.decode() 
     guard let obj = object else { 
      fatalError("fail to init object with \(dictionary)") 
     } 
     self = obj 
    } 

然後創建您的對象作爲符合y Codable協議的結構。它看起來像：

struct User: Codable { 
    var name: String? 
    var nickname: String? 
    ... 
    // If needed declare CodingKey here 
    // enum CodingKeys: String, CodingKey { 
    //  case date = "dateOfBirth" 
    //  ... 
    // } 
} 

struct Movies: Codable { 
    var name: String? 
    var year: Int? 
} 

現在你需要提取從你的迴應你的數據字典和應用新的初始化方法：

if let dic = json["data"] as? [String: Any] { 
    let user: User = User(with: dic) 
    // Do stuff here 
} 

如果數據突然變成一個數組，你將不得不處理它的方式不同（如本例中的用戶數組）