如何使用 ISO 8601 和 RFC 3339 的格式标准生成日期时间戳?
目标是生成如下字符串:
"2015-01-01T00:00:00.000Z"
格式:
最佳情况:
我搜索了 StackOverflow、Google、Apple 等,都没有找到 Swift 的答案。
最有希望的类是 NSDate
、NSDateFormatter
、NSTimeZone
。
相关问答:https://stackoverflow.com/questions/16254575/how-do-i-get-iso-8601-date-in-ios
这是我目前想到的最好的方法:
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))
Swift 4 - iOS 11.2.1 或更高版本
extension ISO8601DateFormatter {
convenience init(_ formatOptions: Options, timeZone: TimeZone = TimeZone(secondsFromGMT: 0)!) {
self.init()
self.formatOptions = formatOptions
self.timeZone = timeZone
}
}
extension Formatter {
static let iso8601 = ISO8601DateFormatter([.withInternetDateTime, .withFractionalSeconds])
}
extension Date {
var iso8601: String {
return Formatter.iso8601.string(from: self)
}
}
extension String {
var iso8601: Date? {
return Formatter.iso8601.date(from: self)
}
}
使用方法
Date().description(with: .current) // Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
let dateString = Date().iso8601 // "2019-02-06T00:35:01.746Z"
if let date = dateString.iso8601 {
date.description(with: .current) // "Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
print(date.iso8601) // "2019-02-06T00:35:01.746Z\n"
}
**iOS 9 - Swift 3 或更高版本***
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
}()
}
可编程协议*** >; 如果您需要在使用 Codable 协议时,您可以创建自己的自定义日期编码/解码策略:
extension JSONDecoder.DateDecodingStrategy {
static let iso8601withFractionalSeconds = custom {
let container = try $0.singleValueContainer()
let string = try container.decode(String.self)
guard let date = Formatter.iso8601.date(from: string) else {
throw DecodingError.dataCorruptedError(in: container,
debugDescription: "Invalid date: " + string)
}
return date
}
}
和编码策略
extension JSONEncoder.DateEncodingStrategy {
static let iso8601withFractionalSeconds = custom {
var container = $1.singleValueContainer()
try container.encode(Formatter.iso8601.string(from: $0))
}
}
游乐场测试
let dates = [Date()] // ["Feb 8, 2019 at 9:48 PM"]
编码
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601withFractionalSeconds
let data = try! encoder.encode(dates)
print(String(data: data, encoding: .utf8)!)
解码
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601withFractionalSeconds
let decodedDates = try! decoder.decode([Date].self, from: data) // ["Feb 8, 2019 at 9:48 PM"]
[!在此输入图片描述][2]
请记住按照 Technical Q&A1480 中的说明将 locale 设置为 en_US_POSIX
。在 Swift 3:
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ"
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.locale = Locale(identifier: "en_US_POSIX")
print(formatter.string(from: date))
问题在于,如果您的设备使用的是非格里高利历,那么除非您指定 locale
以及 timeZone
和 dateFormat
字符串,否则年份将不符合 RFC3339/ISO8601 标准。
你也可以使用 ISO8601DateFormatter
来摆脱自己设置 locale
和 timeZone
的麻烦:
let date = Date()
let formatter = ISO8601DateFormatter()
formatter.formatOptions.insert(.withFractionalSeconds) // this is only available effective iOS 11 and macOS 10.13
print(formatter.string(from: date))
有关 Swift 2 的示例,请参阅 本答案的上一修订版本。
在我的案例中,我必须将 DynamoDB - lastUpdated 列(Unix 时间戳)转换为正常时间。
lastUpdated 的初始值为:1460650607601 - 通过 :
if let lastUpdated : String = userObject.lastUpdated {
let epocTime = NSTimeInterval(lastUpdated)! / 1000 // convert it from milliseconds dividing it by 1000
let unixTimestamp = NSDate(timeIntervalSince1970: epocTime) //convert unix timestamp to Date
let dateFormatter = NSDateFormatter()
dateFormatter.timeZone = NSTimeZone()
dateFormatter.locale = NSLocale.currentLocale() // NSLocale(localeIdentifier: "en_US_POSIX")
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
dateFormatter.dateFromString(String(unixTimestamp))
let updatedTimeStamp = unixTimestamp
print(updatedTimeStamp)
}