如何使用Decodable解码JSON数组？
如何使用Decodable解码JSON数组？
提问于 2017-12-12 20:34:02
我正在请求API发送一些数据给我，我可以成功检索，但我被困在它的解码过程中。下面是我收到的JSON：
[
{
"challenge_id":1,
"challenge_title":"newchallenge1",
"challenge_pts_earned":1000,
"challenge_description":"description1",
"start_date":"2017-09-24T00:00:00.000Z",
"end_date":"2017-09-24T00:00:00.000Z",
"challenge_category_id":1,
"status_id":2,
"createdAt":"2017-09-24T17:21:47.000Z",
"updatedAt":"2017-09-24T09:40:34.000Z"
},
{
"challenge_id":2,
"challenge_title":"challenge1",
"challenge_pts_earned":100,
"challenge_description":"description1",
"start_date":"2017-09-24T00:00:00.000Z",
"end_date":"2017-09-24T00:00:00.000Z",
"challenge_category_id":1,
"status_id":0,
"createdAt":"2017-09-24T17:22:12.000Z",
"updatedAt":"2017-09-24T09:22:12.000Z"
},
{
"challenge_id":3,
"challenge_title":"new eat title",
"challenge_pts_earned":600000,
"challenge_description":"haha",
"start_date":"2017-01-09T00:00:00.000Z",
"end_date":"2017-01-10T00:00:00.000Z",
"challenge_category_id":2,
"status_id":0,
"createdAt":"2017-09-27T17:12:10.000Z",
"updatedAt":"2017-09-27T09:15:19.000Z"
}
]我正在尝试创建以下结构来解码它：
struct challenge : Codable {
let id : String?
let title : String?
let pointsEarned : String?
let description : String?
let dayStarted : String?
let dayEnded : String?
let categoryID : String?
let statusID : Int?
let createdAt : Date?
let updatedAt : Date?
enum CodingKeys: String, CodingKey {
case id = "challenge_id"
case title = "challenge_title"
case pointsEarned = "challenge_pts_earned"
case description = "challenge_description"
case dayStarted = "start_date"
case dayEnded = "end_date"
case categoryID = "challenge_category_id"
case statusID = "status_id"
case createdAt, updatedAt
}
}下面是我的实现代码：
var All_challenges : [challenge]?
let url = URL(string: API.all_challenges.rawValue)!
var request = URLRequest(url: url)
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "GET"
let task = URLSession.shared.dataTask(with: request) { data, response, error in
guard let data = data, error == nil else {
print("error=\(String(describing: error))")
return
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("\(String(describing: response))")
}
let responseString = String(data: data, encoding: .utf8)
guard let result = responseString else { return }
print(result)
if let json = try? JSONDecoder().decode([challenge].self , from : data ) {
self.All_challenges = json
}
}
task.resume()然而，当我尝试调试它时，我永远不能输入if语句
if let json = try? JSONDecoder().decode([challenge].self,from:data ) {
self.All_challenges = json
}请给我一些描述我的错误在哪里，我是JSON解析的新手
回答 1
Stack Overflow用户
发布于 2017-12-12 21:12:18
您的代码中有几个错误。首先，你的一些变量类型是错误的。所有id%s和challenge_pts_earned都需要是Int类型。您可以很容易地发现这一点，因为在JSON中，字符串需要用引号分隔。在对Date进行解码时，还需要指定要使用的日期格式。
startDate和endDate也是dates，所以即使可以将它们解码为Strings，我也建议您将它们存储为实际的Date对象。
还请遵守Swift命名约定，即类型为upperCamelCase，变量和函数名称为lowerCamelCase。您可以使用符合CodingKey的自定义类型将您的自定义变量名映射到它们的JSON表示。
struct Challenge : Decodable {
let id: Int?
let title: String?
let pointsEarned: Int?
let description: String?
let startDate: String?
let endDate: String?
let categoryId: Int?
let statusId: Int?
let createdAt: Date?
let updatedAt: Date?
private enum CodingKeys: String, CodingKey {
case id = "challenge_id"
case title = "challenge_title"
case pointsEarned = "challenge_pts_earned"
case description = "challenge_description"
case startDate = "start_date"
case endDate = "end_date"
case categoryId = "challenge_category_id"
case statusId = "status_id"
case createdAt
case updatedAt
}
static var dateFormatter: DateFormatter {
let df = DateFormatter()
df.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
df.locale = Locale(identifier: "en_US_POSIX")
return df
}
}
do {
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(Challenge.dateFormatter)
let decoded = try decoder.decode([Challenge].self, from: jsonArrayResponse.data(using: .utf8)!)
} catch {
print(error)
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/47772779
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