如何在尝试解码 JSON 时修复 Xcode 中的错误 "mismatch"

Question

我是 Swift 语言的新手，我正在尝试在 Xcode.

中构建一个简单的 JSON 解析应用程序

这是我得到的一个错误： typeMismatch(Swift.Double, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "Date", intValue: nil) ], debugDescription: “预期解码 Double 但发现了 string/data。”, underlyingError: nil))

这里有一个link要解析的：https://www.cbr-xml-daily.ru/daily_json.js

我有什么型号的：（我用https://app.quicktype.io创建的）

struct Welcome: Codable {
    var date, previousDate: Date
    var previousURL: String
    var timestamp: Date
    var valute: [String: Valute]

    enum CodingKeys: String, CodingKey {
        case date = "Date"
        case previousDate = "PreviousDate"
        case previousURL = "PreviousURL"
        case timestamp = "Timestamp"
        case valute = "Valute"
    }
}

struct Valute: Codable {
    var id, numCode, charCode: String
    var nominal: Int
    var name: String
    var value, previous: Double

    enum CodingKeys: String, CodingKey {
        case id = "ID"
        case numCode = "NumCode"
        case charCode = "CharCode"
        case nominal = "Nominal"
        case name = "Name"
        case value = "Value"
        case previous = "Previous"
    }
}

解析解码代码如下：

func request(urlString: String, completion: @escaping (Welcome?, Error?) -> Void) {
    guard let url = URL(string: urlString) else { return }
    
    URLSession.shared.dataTask(with: url) { (data, response, error) in
        if let error = error {
            print("Some error")
            completion(nil, error)
            return
        } else {
            guard let data = data else { return }
            do {
                let welcome = try JSONDecoder().decode(Welcome.self, from: data)
                completion(welcome, nil)
            } catch let jsonError {
                print("Failed to decode JSON: \(jsonError)")
                completion(nil, jsonError)
            }
            
        }
    } .resume()
}

非常感谢任何help/advice。

Answer 1

这是因为您没有正确解码 Date。

尝试为您的 JSONDecoder 设置 dateDecodingStrategy:

do {
    let decoder = JSONDecoder()
    decoder.dateDecodingStrategy = .iso8601
    let welcome = try decoder.decode(Welcome.self, from: data)
    completion(welcome, nil)
} catch let jsonError {
    print("Failed to decode JSON: \(jsonError)")
    completion(nil, jsonError)
}