Swift Codable 多种类型

Question

我尝试解析返回json对象的api。我的问题是有些键有时是一个字符串，有时是一个对象，如以下示例中的键"Value"：

[
{
"Description": null,
"Group": "Beskrivning av enheten",
"GroupDescription": null,
"Id": "Description",
"Name": "Mer om enheten",
"Value": "Det finns möjlighet till parkering på gatorna runt om, men det är kantstenar och ganska branta backar för att komma upp till lekplatsen.rnrnUtanför själva lekplatsen finns en gungställning med en plan omväg in. Alla lekredskap står i sandytor, det finns många kanter. Runt hela lekplatsen går ett staket med öppningar i olika riktningar."
},
{
"Description": null,
"Group": "Bilder och film",
"GroupDescription": null,
"Id": "Image",
"Name": "Huvudbild",
"Value": {
"__type": "FileInfo",
"Id": "8871b3b1-14f4-4054-8728-636d9da21ace",
"Name": "ullerudsbacken.jpg"
}
}
]

我的结构如下所示：

struct ServiceUnit: Codable {
let description: String?
let group: String?
let groupDescription: String?
let id: String
let name: String
var value: String?
struct ServiceUnitTypeInfo: Codable {
let id: String
let singularName: String?
enum CodingKeys: String, CodingKey {
case id = "Id"
case singularName = "SingularName"
}
}
let serviceUnitTypeInfo: ServiceUnitTypeInfo?
let values: [String]?
enum CodingKeys: String, CodingKey {
case description = "Description"
case group = "Group"
case groupDescription = "GroupDescription"
case id = "Id"
case name = "Name"
case value = "Value"
case serviceUnitTypeInfo = "ServiceUnitTypeInfo"
case values = "Values"
case image = "Image"
}
}

我必须管理我完全迷路了(是的，我是 swift 的初学者(，我找不到解决问题的方法。我知道我必须使用自定义初始化，但我不知道如何操作。

Answer 1

你可以试试

struct Root: Codable {
let description,id: String
let group,groupDescription: String?
let name: String
let value: MyValue
enum CodingKeys: String, CodingKey {
case description = "Description"
case group = "Group"
case groupDescription = "GroupDescription"
case id = "Id"
case name = "Name"
case value = "Value"
}
}
enum MyValue: Codable {
case string(String)
case innerItem(InnerItem)
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if let x = try? container.decode(String.self) {
self = .string(x)
return
}
if let x = try? container.decode(InnerItem.self) {
self = .innerItem(x)
return
}
throw DecodingError.typeMismatch(MyValue.self, DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Wrong type for MyValue"))
}
func encode(to encoder: Encoder) throws {
var container = encoder.singleValueContainer()
switch self {
case .string(let x):
try container.encode(x)
case .innerItem(let x):
try container.encode(x)
}
}
}
struct InnerItem: Codable {
let type, id, name: String
enum CodingKeys: String, CodingKey {
case type = "__type"
case id = "Id"
case name = "Name"
}
}

---

do {
let result = try JSONDecoder().decode([Root].self,from:data)
print(result)
}
catch {
print(error)
}

Answer 2

基于@Sh_Khan的答案并回答评论中的@Nikhi问题(如何访问值(，我想将其添加到枚举声明中：

var innerItemValue: InnerItem? {
switch self {
case .innerItem(let ii):
return ii
default:
return nil
}
}
var stringValue: String? {
switch self {
case .string(let s):
return s
default:
return nil
}
}