Swift IOS 无法使用 Codable 访问 json 数组数据

Question

如何使用Codable访问JSON。 这是我的示例 JSON。

{
"status": "success",
"message": "Data received successfully",
"course": {
"id": 1,
"description": "something",
"name": "ielts",
"attachments": [
{
"id": 809,
"attachment": "https:--",
"file_name": "syllabus.pdf",
"description": "course",
},
{
"id": 809,
"attachment": "https:--",
"file_name": "syllabus.pdf",
"description": "course",
}]
"upcased_name": "IELTS"
}
}

这是我的代码。

struct ResponseObject: Codable {
let course: [Course]
}
struct Course: Codable {
let id: Int
let name: String
let description: String
let attachments: [Attachments]
}
struct Attachments: Codable {
let id: Int
let attachment: String
let file_name: String
let description: String
let about: String
}
var course: [Course] = []

这是我的 api 调用。

func fetchUserData() {
let headers: HTTPHeaders = [
"Authorization": "Token token="+UserDefaults.standard.string(forKey: "auth_token")!,
"Accept": "application/json"
]
let params = ["course_id" : "1"] as [String : AnyObject]
self.showSpinner("Loading...", "Please wait!!")
DispatchQueue.global(qos: .background).async {
AF.request(SMAConstants.courses_get_course_details , parameters: params, headers:headers ).responseDecodable(of: ResponseObject.self, decoder: self.decoder) { response in
DispatchQueue.main.async {
self.hideSpinner()
guard let value = response.value else {
print(response.error ?? "Unknown error")
return
}
self.course = value.course
}
}
}
}

}

我收到以下错误。

响应序列化失败(原因： Alamofire.AFError.ResponseSerializationFailureReason.decodingFailed(error： Swift.DecodingError.typeMismatch(Swift.Array， Swift.DecodingError.Context(codingPath： [CodingKeys(stringValue： "course"， intValue： nil(]， debugDescription： "预期解码 数组，但找到了字典。

Answer 1

您的模型对象与 JSON 结构不匹配。试试这个：

struct ResponseObject: Codable {
let status, message: String
let course: Course
}
struct Course: Codable {
let id: Int
let courseDescription, name: String
let attachments: [Attachment]
let upcasedName: String
enum CodingKeys: String, CodingKey {
case id
case courseDescription = "description"
case name, attachments
case upcasedName = "upcased_name"
}
}
struct Attachment: Codable {
let id: Int
let attachment, fileName, attachmentDescription: String
enum CodingKeys: String, CodingKey {
case id, attachment
case fileName = "file_name"
case attachmentDescription = "description"
}
}

要使用普通的 Swift 和 Foundation 下载和解析它，请使用如下代码：

let url = URL(string: SMAConstants.courses_get_course_details)!
let task = URLSession.shared.dataTask(with: url) { data, response, error in
if let error = error {
print(error)
return
}
if let data = data {
do {
let response = try JSONDecoder().decode(ResponseObject.self, from: data)
// access your data here
} catch {
print(error)
}
}
}
task.resume()