ISO8601DateFormatter 不解析 ISO 日期字符串

Question

我正在尝试解析这个

2017-01-23T10:12:31.484Z

使用 iOS 10 提供的原生 ISO8601DateFormatter 类，但总是失败。 如果字符串不包含毫秒，则Date 对象的创建没有问题。

我尝试过这个和许多options 组合，但总是失败...

let formatter = ISO8601DateFormatter()
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.formatOptions = [.withInternetDateTime, .withDashSeparatorInDate, .withColonSeparatorInTime, .withColonSeparatorInTimeZone, .withFullTime]

有什么想法吗？ 谢谢！

Answer 1

在 macOS 10.13 / iOS 11 ISO8601DateFormatter 之前不支持包含毫秒的日期字符串。

一种解决方法是使用正则表达式删除毫秒部分。

let isoDateString = "2017-01-23T10:12:31.484Z"
let trimmedIsoString = isoDateString.replacingOccurrences(of: "\\.\\d+", with: "", options: .regularExpression)
let formatter = ISO8601DateFormatter()
let date = formatter.date(from: trimmedIsoString)

在 macOS 10.13+ / iOS 11+ 中添加了一个新选项以支持小数秒：

static var withFractionalSeconds: ISO8601DateFormatter.Options { get }

let isoDateString = "2017-01-23T10:12:31.484Z"
let formatter = ISO8601DateFormatter()
formatter.formatOptions =  [.withInternetDateTime, .withFractionalSeconds]
let date = formatter.date(from: isoDateString)

Answer 2

对于尚未准备好使用 iOS 11 的人，您可以随时创建自己的格式化程序来处理毫秒，例如：

extension DateFormatter {
    static var iSO8601DateWithMillisec: DateFormatter {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
        return dateFormatter
    }
}

用法：

let formater = DateFormatter.iSO8601DateWithMillisec
let date = formater.date(from: "2017-01-23T10:12:31.484Z")!
print(date) // output: 2017-01-23 10:12:31 +0000

这比编写一个正则表达式从输入字符串中去除毫秒要优雅一些。

Answer 3

也许这将有助于解码略有不同的格式：

extension JSONDecoder {
    enum DateDecodeError: String, Error {
        case invalidDate
    }

    static var bestDateAttemptDecoder: JSONDecoder {
        let decoder = JSONDecoder()
        decoder.dateDecodingStrategy = .custom({ (decoder) -> Date in
            let container = try decoder.singleValueContainer()
            if let dateSecs = try? container.decode(Double.self) {
                return Date(timeIntervalSince1970: dateSecs)
            }

            if let dateSecs = try? container.decode(UInt.self) {
                return Date(timeIntervalSince1970: TimeInterval(dateSecs))
            }

            let dateStr = try container.decode(String.self)
            let isoFormatter = ISO8601DateFormatter()
            isoFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
            if let date = isoFormatter.date(from: dateStr) {
                return date
            }

            isoFormatter.formatOptions = [.withInternetDateTime ]
            if let date = isoFormatter.date(from: dateStr) {
                return date
            }

            log.warning("Cannot decode date");
            throw DateDecodeError.invalidDate
        })

        return decoder
    }
}

发件人：https://gist.github.com/th3m477/442a0d1da6354dd3b84e3b71df5dca6a

Answer 4

几个月前我遇到了同样的问题。这是我的参考解决方案：

// *****************************************
// MARK: - Formatter extension
// *****************************************
extension Formatter {
    static let iso8601: ISO8601DateFormatter = {
        let formatter = ISO8601DateFormatter()
        formatter.timeZone = TimeZone.current 
        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
        return formatter
    }()
    static let iso8601NoSecond: ISO8601DateFormatter = {
        let formatter = ISO8601DateFormatter()
        formatter.timeZone = TimeZone.current 
        formatter.formatOptions = [.withInternetDateTime]
        return formatter
    }()
}

// *****************************************
// MARK: - ISO8601 helper
// *****************************************
    func getDateFrom(DateString8601 dateString:String) -> Date?
    {
        if let date = Formatter.iso8601.date(from: dateString)  {
            return date
        }
        if let date = Formatter.iso8601NoSecond.date(from: dateString)  {
            return date
        }
        return nil
    }

// *****************************************
// usage
// *****************************************
    let d = getDateFrom(DateString8601: "2017-01-23T10:12:31.484Z")
    print("2017-01-23T10:12:31.484Z millis= ", d?.timeIntervalSinceReferenceDate)

    let d2 = getDateFrom(DateString8601: "2017-01-23T10:12:31Z")
    print("2017-01-23T10:12:31Z millis= ", d2?.timeIntervalSinceReferenceDate)


// *****************************************
// result
// *****************************************
2017-01-23T10:12:31.484Z millis=  Optional(506859151.48399997)
2017-01-23T10:12:31Z millis=  Optional(506859151.0)