Swift：如何创建日期时间戳和格式作为ISO 8601，RFC 3339，UTC时区？ [英] Swift: how to create a date time stamp and format as ISO 8601, RFC 3339, UTC time zone?

问题描述

如何生成日期时间戳，使用

How to generate a date time stamp, using the format standards for ISO 8601 and RFC 3339?

The goal is a string that looks like this:

"2015-01-01T00:00:00.000Z"

Format:

• year, month, day, as "XXXX-XX-XX"
• the letter "T" as a separator
• hour, minute, seconds, milliseconds, as "XX:XX:XX.XXX".
• the letter "Z" as a zone designator for zero offset, a.k.a. UTC, GMT, Zulu time.

Best case:

• Swift source code that is simple, short, and straightforward.
• No need to use any additional framework, subproject, cocoapod, C code, etc.

I've searched StackOverflow, Google, Apple, etc. and haven't found a Swift answer to this.

The classes that seem most promising are NSDate, NSDateFormatter, NSTimeZone.

Related Q&A: How do I get ISO 8601 date in iOS?

Here's the best I've come up with so far:

var now = NSDate()
var formatter = NSDateFormatter()
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
println(formatter.stringFromDate(now))

解决方案

Xcode 8.2 • Swift 3.0.2

extension Formatter {
    static let iso8601: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.timeZone = TimeZone(secondsFromGMT: 0)
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
        return formatter
    }()
}
extension Date {
    var iso8601: String {
        return Formatter.iso8601.string(from: self)
    }
}

extension String {
    var dateFromISO8601: Date? {
        return Formatter.iso8601.date(from: self)   // "Mar 22, 2017, 10:22 AM"
    }
}

---

Usage:

let stringFromDate = Date().iso8601    // "2017-03-22T13:22:13.933Z"

if let dateFromString = stringFromDate.dateFromISO8601 {
    print(dateFromString.iso8601)      // "2017-03-22T13:22:13.933Z"
}

---

Xcode 7.3.1 • Swift 2.2.1

extension NSDate {
    struct Formatter {
        static let iso8601: NSDateFormatter = {
            let formatter = NSDateFormatter()
            formatter.calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierISO8601)
            formatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
            formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
            formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
            return formatter
        }()
    }
    var iso8601: String { return Formatter.iso8601.stringFromDate(self) }
}

extension String {
    var dateFromISO8601: NSDate? {
        return NSDate.Formatter.iso8601.dateFromString(self)
    }
}

---

Usage:

let stringFromDate = NSDate().iso8601    // "2016-06-18T05:18:27.935Z"

if let dateFromString = stringFromDate.dateFromISO8601 {
    print(dateFromString.iso8601)      // "2016-06-18T05:18:27.935Z"
}

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