如何将模型对象转换为 JSON - Swift 4

Posted 2023-03-15

【中文标题】如何将模型对象转换为 JSON - Swift 4

【英文标题】：How to Convert a model object into JSON - Swift 4

【发布时间】：2018-01-25 05:28:38

【问题描述】：

如何将模型对象转换为 JSON？ 我想要“Answer”对象。

// 答案类

class Answers 

    var cat_id: String!
    var responses = [Response]()
    var date: String!
    var comment: String!
    var time: String!
    var lat: String!
    var lon: String!
    var address: String!

// 响应类

class Response 

    var que_id: String!
    var question: String!
    var response: String!

【问题讨论】：

How to serialize or convert Swift objects to JSON?的可能重复

试试这个：***.com/a/10548511/5167909

不相关但 NEVER 将类中的属性声明为隐式未包装的选项，作为不编写初始化程序的不在场证明。属性应该是可选的，然后将它们声明为常规可选（?），否则声明为非可选（无问号和感叹号）

【参考方案1】：

使两种类型都符合Codable:

class Answers: Codable 
    ...


class Response: Codable 
    ...

然后使用JSONEncoder:

let answers: Answers = ...

do 
    let data = try JSONEncoder().encode(answers)
    // use data here
 catch 
    print(error)

见Encoding and Decoding Custom Types。

【参考方案2】：

如果您使用的是 swift4，您可以使用可编码和可解码协议。我仍在处理异构对象列表。但这应该对你有用。让你的类符合ABEncodable。

protocol ABDecodable: Decodable 
    static func decodeFromData(_ data: Data) -> Decodable?


protocol ABEncodable: Encodable 
    static func encodeFromObject<T>(_ object: T) -> Data? where T: Encodable


extension ABDecodable 
    static func decodeFromData(_ data: Data) -> Decodable? 
        do 
            return try JSONDecoder().decode(self, from: data)
        
        catch 
            print(error)
        
        return nil
    


extension ABEncodable 
    static func encodeFromObject<T>(_ object: T) -> Data? where T: Encodable 
        do 
            return try JSONEncoder().encode(object)
        
        catch 
            return nil
        
    



//MARK: Decode mapper class
//Send jsonString or data to decode it into an required Object
final class Decode<T: Decodable> 
    private func decodeData(_ data: Data) -> T? 
        if let klass = T.self as? ABDecodable.Type 
            if let object = klass.decodeFromData(data) as? T 
                return object
            
        
        else 
            do 
                return try JSONDecoder().decode(T.self, from: data)
            
            catch 
                print(error)
            
        
        return nil
    

    func fromJsonString(_ json: String) -> T? 
        guard let data = json.data(using: String.Encoding.utf8) else  return nil 

        if let object = decodeData(data) 
            return object
        
        return nil
    
    func fromData(_ data: Data) -> T? 
        if let object = decodeData(data) 
            return object
        
        return nil
    


//MARK: Encode mapper class
//Send jsonString or data to decode it into an required Object

final class Encode<N:Encodable> 

    private func encodeObject(_ object: N) -> Data? 
        if let klass = N.self as? ABEncodable.Type 
            if let data = klass.encodeFromObject(object) 
                return data
            
        
        else 
            do 
                return try JSONEncoder().encode(object)
            
            catch 
                print(error)
            
        

        return nil
    

    func toJsonString(_ object: N) -> String? 
        if let data = encodeObject(object) 
            return String(data: data, encoding: .utf8)
        
        return nil
    

    func toData(_ object: N) -> Data? 
        if let data = encodeObject(object) 
            return data
        
        return nil