json - 在 Swift 中从 String 或 TimeInterval 解码日期/时间

Question

我有一个 JSON(来自第三方)需要解析。此 JSON 返回多个嵌套对象

articles: {
  authors: {
    birthday: 'DD-MM-YYYY'
  }
  relevant_until: 'YYYY-MM-DD HH:MM:SS'
  publication_date: secondsSince1970,
  last_comment: iso8601
}

我正在关注 this answer拥有多个日期格式化程序并且它可以工作，只要从 JSON 中提取的每个日期都是一个字符串。

但是当涉及到 secondsSince1970(UNIX epoc 时间)时，我找不到将其解析为可编码对象的方法。我到处都看到 Date(timeIntervalSince1970: timestamp) 但我不知道如何在解码时使用它

当日期可以作为 TimeInterval 或字符串传递时，如何解析此对象上的日期？

try jsonDecoder.decode(Articles.self, from: jsonData)

Answer 1

extension Formatter {
    static let iso8601withFractionalSeconds: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS"
        return formatter
    }()
    static let iso8601: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
        return formatter
    }()
    static let ddMMyyyy: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "dd-MM-yyyy"
        return formatter
    }()
}

---

extension JSONDecoder.DateDecodingStrategy {
    static let multiple = custom {
        let container = try $0.singleValueContainer()
        do {
            return try Date(timeIntervalSince1970: container.decode(Double.self))
        } catch DecodingError.typeMismatch {
            let string = try container.decode(String.self)
            if let date = Formatter.iso8601withFractionalSeconds.date(from: string) ??
                Formatter.iso8601.date(from: string) ??
                Formatter.ddMMyyyy.date(from: string) {
                return date
            }
            throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid date: \(string)")
        }
    }
}

---

Playground 测试:

struct Root: Codable {
    let articles: Articles
}
struct Articles: Codable {
    let authors: Authors
    let relevantUntil: Date
    let publicationDate: Date
    let lastComment: Date
}

struct Authors: Codable {
    let birthday: Date
}

---

let json = """
{"articles": {
              "authors": {"birthday": "01-01-1970"},
              "relevant_until": "2020-11-19 01:23:45",
              "publication_date": 1605705003.0019,
              "last_comment": "2020-11-19 01:23:45.678"}
}
"""

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .multiple
decoder.keyDecodingStrategy = .convertFromSnakeCase

do {
    let root = try decoder.decode(Root.self, from: .init(json.utf8))
    print(root.articles)  // Articles(authors: __lldb_expr_107.Authors(birthday: 1970-01-01 03:00:00 +0000), relevantUntil: 2020-11-19 04:23:45 +0000, publicationDate: 2020-11-18 13:10:03 +0000, lastComment: 2020-11-19 04:23:45 +0000)

} catch {
    print(error)
}