JSONEncoderencode始终为空

问题描述

我有一堂课，下一堂课

import UIKit

final class PruebaModel: Codable {
    
    let a: String?
    let b: String?
    let c: [D]?
    let f: String?
    
    
    enum CodingKeys: String,CodingKey {
        case a = "a"
        case b = "b"
        case c = "c"
        case f = "f"
    }
    
    required init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        a = try values.decodeIfPresent(String.self,forKey: .a)
        b = try values.decodeIfPresent(String.self,forKey: .b)
        c = try values.decodeIfPresent([D].self,forKey: .c)
        f = try values.decodeIfPresent(String.self,forKey: .f)
    }
    
    required init()  {
        a = ""
        b = ""
        c = Array<D>()
        f = ""
    }
}


import Foundation

struct D: Codable {
    let l: String
    let m: String
    
    enum CodingKeys: String,CodingKey {
        case l = "l"
        case m = "m"
    }
    
    init(from decoder: Decoder) throws {
        let value = try decoder.container(keyedBy: CodingKeys.self)
        l = try value.decode(String.self,forKey: .l)
        m = try value.decode(String.self,forKey: .m)
    }
    
    public func encode(to encoder: Encoder) throws {
        //Implement when needed
    }
}

json是下一个

{
     
     "a": "a","b": "b","c": [
       {
         "l": "¿Cuál es el mi color favorito?","m":"QAUY.15"
       }
    ],"f": "f"
     
}

该类是完美的，它具有带参数的对象，但是当我尝试将其转换为json时。数组为空

代码

let jsonData = try! JSONEncoder().encode(PruebaModel)
let jsonString = String(data: jsonData,encoding: .utf8)!

当我评估表达式时的结果

po String(data: try! JSONEncoder().encode(PruebaModel),encoding: .utf8)!

“ {” a“：” a“，” b“：” b“，” c“：[{}]，” f“：” f“}”

为什么c为空？它在数组内部有一个对象。

如果对象在数组内部没有特殊字符，则解码将显示该对象

解决方法

不清楚您要问什么。一方面，您有太多的代码。另外，您显示的代码没有任何意义。另一方面，您显示的JSON可以很好地解码为PruebaModel，正确构造的PruebaModel可以编码为您的JSON：

struct D: Codable {
    let l: String
    let m: String
}
struct PruebaModel: Codable {
    let a: String?
    let b: String?
    let c: [D]?
    let f: String?
}
let jsonString = """
{
    "a": "a","b": "b","c": [
        {
            "l": "¿Cuál es el mi color favorito?","m":"QAUY.15"
        }
    ],"f": "f"
    }
"""
let jsonData = jsonString.data(using: .utf8)!
let result = try? JSONDecoder().decode(PruebaModel.self,from: jsonData)
print(result?.c?.first?.l) // Optional("¿Cuál es el mi color favorito?")
// let's also try encoding
let d = D(l: "¿Cuál es el mi color favorito?",m: "QAUY.15")
let myPruebaModel = PruebaModel(a: "a",b: "b",c: [d],f: "f")
let jsonData2 = try? JSONEncoder().encode(myPruebaModel)
print(String(data: jsonData2!,encoding: .utf8)!)
// {"b":"b","c":[{"l":"¿Cuál es el mi color favorito?","m":"QAUY.15"}],"a":"a","f":"f"}