Related
I am trying to get an Int value for Hour from a string.
let time = 13:24
func getNtfHour() -> Date{
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH"
let result = dateFormatter.date(from: time)!
return result //2000-01-01 08:24:00 +0000
}
As you can see my current code return a whole date and the time does not match with the string. How do I fix it?
edit: I managed to to this by using date components
let time = 13:24
func getNtfHour() -> Int{
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"
let result = dateFormatter.date(from: time)!
let calendar = Calendar.current.component(.hour, from: result)
return calendar //13
}
As a time string is actually not related to a Dateformatter an easier way is to parse the string directly.
If the hour has always two digits
let time = "13:24"
let hour = Int(time.prefix(2))
or otherwise
let time = "13:24"
if let range = time.range(of: "^\\d+", options: .regularExpression) {
let hour = Int(time[range])
}
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 an ISO 8601 date on 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))
Swift 4 • iOS 11.2.1 or later
extension ISO8601DateFormatter {
convenience init(_ formatOptions: Options) {
self.init()
self.formatOptions = formatOptions
}
}
extension Formatter {
static let iso8601withFractionalSeconds = ISO8601DateFormatter([.withInternetDateTime, .withFractionalSeconds])
}
extension Date {
var iso8601withFractionalSeconds: String { return Formatter.iso8601withFractionalSeconds.string(from: self) }
}
extension String {
var iso8601withFractionalSeconds: Date? { return Formatter.iso8601withFractionalSeconds.date(from: self) }
}
Usage:
Date().description(with: .current) // Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
let dateString = Date().iso8601withFractionalSeconds // "2019-02-06T00:35:01.746Z"
if let date = dateString.iso8601withFractionalSeconds {
date.description(with: .current) // "Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
print(date.iso8601withFractionalSeconds) // "2019-02-06T00:35:01.746Z\n"
}
iOS 9 • Swift 3 or later
extension Formatter {
static let iso8601withFractionalSeconds: 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
}()
}
Codable Protocol
If you need to encode and decode this format when working with Codable
protocol you can create your own custom date encoding/decoding strategies:
extension JSONDecoder.DateDecodingStrategy {
static let iso8601withFractionalSeconds = custom {
let container = try $0.singleValueContainer()
let string = try container.decode(String.self)
guard let date = Formatter.iso8601withFractionalSeconds.date(from: string) else {
throw DecodingError.dataCorruptedError(in: container,
debugDescription: "Invalid date: " + string)
}
return date
}
}
and the encoding strategy
extension JSONEncoder.DateEncodingStrategy {
static let iso8601withFractionalSeconds = custom {
var container = $1.singleValueContainer()
try container.encode(Formatter.iso8601withFractionalSeconds.string(from: $0))
}
}
Playground Testing
let dates = [Date()] // ["Feb 8, 2019 at 9:48 PM"]
encoding
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601withFractionalSeconds
let data = try! encoder.encode(dates)
print(String(data: data, encoding: .utf8)!)
decoding
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601withFractionalSeconds
let decodedDates = try! decoder.decode([Date].self, from: data) // ["Feb 8, 2019 at 9:48 PM"]
Remember to set the locale to en_US_POSIX as described in Technical Q&A1480. In Swift 3:
let date = Date()
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ"
print(formatter.string(from: date))
The issue is that if you're on a device which is using a non-Gregorian calendar, the year will not conform to RFC3339/ISO8601 unless you specify the locale as well as the timeZone and dateFormat string.
Or you can use ISO8601DateFormatter to get you out of the weeds of setting locale and timeZone yourself:
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))
For Swift 2 rendition, see previous revision of this answer.
If you want to use the ISO8601DateFormatter() with a date from a Rails 4+ JSON feed (and don't need millis of course), you need to set a few options on the formatter for it to work right otherwise the the date(from: string) function will return nil. Here's what I'm using:
extension Date {
init(dateString:String) {
self = Date.iso8601Formatter.date(from: dateString)!
}
static let iso8601Formatter: ISO8601DateFormatter = {
let formatter = ISO8601DateFormatter()
formatter.formatOptions = [.withFullDate,
.withTime,
.withDashSeparatorInDate,
.withColonSeparatorInTime]
return formatter
}()
}
Here's the result of using the options versus not in a playground screenshot:
Swift 5
If you're targeting iOS 11.0+ / macOS 10.13+, you simply use ISO8601DateFormatter with the withInternetDateTime and withFractionalSeconds options, like so:
let date = Date()
let iso8601DateFormatter = ISO8601DateFormatter()
iso8601DateFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
let string = iso8601DateFormatter.string(from: date)
// string looks like "2020-03-04T21:39:02.112Z"
To further compliment Andrés Torres Marroquín and Leo Dabus, I have a version that preserves fractional seconds. I can't find it documented anywhere, but Apple truncate fractional seconds to the microsecond (3 digits of precision) on both input and output (even though specified using SSSSSSS, contrary to Unicode tr35-31).
I should stress that this is probably not necessary for most use cases. Dates online do not typically need millisecond precision, and when they do, it is often better to use a different data format. But sometimes one must interoperate with a pre-existing system in a particular way.
Xcode 8/9 and Swift 3.0-3.2
extension Date {
struct Formatter {
static let iso8601: DateFormatter = {
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: .iso8601)
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(identifier: "UTC")
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSXXXXX"
return formatter
}()
}
var iso8601: String {
// create base Date format
var formatted = DateFormatter.iso8601.string(from: self)
// Apple returns millisecond precision. find the range of the decimal portion
if let fractionStart = formatted.range(of: "."),
let fractionEnd = formatted.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: formatted.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
// replace the decimal range with our own 6 digit fraction output
let microseconds = self.timeIntervalSince1970 - floor(self.timeIntervalSince1970)
var microsecondsStr = String(format: "%.06f", microseconds)
microsecondsStr.remove(at: microsecondsStr.startIndex)
formatted.replaceSubrange(fractionRange, with: microsecondsStr)
}
return formatted
}
}
extension String {
var dateFromISO8601: Date? {
guard let parsedDate = Date.Formatter.iso8601.date(from: self) else {
return nil
}
var preliminaryDate = Date(timeIntervalSinceReferenceDate: floor(parsedDate.timeIntervalSinceReferenceDate))
if let fractionStart = self.range(of: "."),
let fractionEnd = self.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: self.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
let fractionStr = self.substring(with: fractionRange)
if var fraction = Double(fractionStr) {
fraction = Double(floor(1000000*fraction)/1000000)
preliminaryDate.addTimeInterval(fraction)
}
}
return preliminaryDate
}
}
Uses ISO8601DateFormatter on iOS10 or newer.
Uses DateFormatter on iOS9 or older.
Swift 4
protocol DateFormatterProtocol {
func string(from date: Date) -> String
func date(from string: String) -> Date?
}
extension DateFormatter: DateFormatterProtocol {}
#available(iOS 10.0, *)
extension ISO8601DateFormatter: DateFormatterProtocol {}
struct DateFormatterShared {
static let iso8601: DateFormatterProtocol = {
if #available(iOS 10, *) {
return ISO8601DateFormatter()
} else {
// iOS 9
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
}
}()
}
In my case I have to convert the DynamoDB - lastUpdated column (Unix Timestamp) to Normal Time.
The initial value of lastUpdated was : 1460650607601 - converted down to 2016-04-14 16:16:47 +0000 via :
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)
}
In the future the format might need to be changed which could be a small head ache having date.dateFromISO8601 calls everywhere in an app. Use a class and protocol to wrap the implementation, changing the date time format call in one place will be simpler. Use RFC3339 if possible, its a more complete representation. DateFormatProtocol and DateFormat is great for dependency injection.
class AppDelegate: UIResponder, UIApplicationDelegate {
internal static let rfc3339DateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
internal static let localeEnUsPosix = "en_US_POSIX"
}
import Foundation
protocol DateFormatProtocol {
func format(date: NSDate) -> String
func parse(date: String) -> NSDate?
}
import Foundation
class DateFormat: DateFormatProtocol {
func format(date: NSDate) -> String {
return date.rfc3339
}
func parse(date: String) -> NSDate? {
return date.rfc3339
}
}
extension NSDate {
struct Formatter {
static let rfc3339: NSDateFormatter = {
let formatter = NSDateFormatter()
formatter.calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierISO8601)
formatter.locale = NSLocale(localeIdentifier: AppDelegate.localeEnUsPosix)
formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
formatter.dateFormat = rfc3339DateFormat
return formatter
}()
}
var rfc3339: String { return Formatter.rfc3339.stringFromDate(self) }
}
extension String {
var rfc3339: NSDate? {
return NSDate.Formatter.rfc3339.dateFromString(self)
}
}
class DependencyService: DependencyServiceProtocol {
private var dateFormat: DateFormatProtocol?
func setDateFormat(dateFormat: DateFormatProtocol) {
self.dateFormat = dateFormat
}
func getDateFormat() -> DateFormatProtocol {
if let dateFormatObject = dateFormat {
return dateFormatObject
} else {
let dateFormatObject = DateFormat()
dateFormat = dateFormatObject
return dateFormatObject
}
}
}
There is a new ISO8601DateFormatter class that let's you create a string with just one line. For backwards compatibility I used an old C-library. I hope this is useful for someone.
Swift 3.0
extension Date {
var iso8601: String {
if #available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *) {
return ISO8601DateFormatter.string(from: self, timeZone: TimeZone.current, formatOptions: .withInternetDateTime)
} else {
var buffer = [CChar](repeating: 0, count: 25)
var time = time_t(self.timeIntervalSince1970)
strftime_l(&buffer, buffer.count, "%FT%T%z", localtime(&time), nil)
return String(cString: buffer)
}
}
}
To complement the version of Leo Dabus, I added support for projects written Swift and Objective-C, also added support for the optional milliseconds, probably isn't the best but you would get the point:
Xcode 8 and Swift 3
extension Date {
struct 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
}()
}
var iso8601: String {
return Formatter.iso8601.string(from: self)
}
}
extension String {
var dateFromISO8601: Date? {
var data = self
if self.range(of: ".") == nil {
// Case where the string doesn't contain the optional milliseconds
data = data.replacingOccurrences(of: "Z", with: ".000000Z")
}
return Date.Formatter.iso8601.date(from: data)
}
}
extension NSString {
var dateFromISO8601: Date? {
return (self as String).dateFromISO8601
}
}
It is now 2022, but I was looking for an answer to this (i.e. how to convert a Date to ISO8601 that includes fractions of seconds). It turns out the answer nowadays is a one-liner:
var somedate: Date = Date.now
var isodate = somedate.ISO8601Format(Date.ISO8601FormatStyle(includingFractionalSeconds: true))
so this will print something like 2022-08-16T17:45:08.548Z
Without some manual String masks or TimeFormatters
import Foundation
struct DateISO: Codable {
var date: Date
}
extension Date{
var isoString: String {
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601
guard let data = try? encoder.encode(DateISO(date: self)),
let json = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: String]
else { return "" }
return json?.first?.value ?? ""
}
}
let dateString = Date().isoString
Based on the acceptable answer in an object paradigm
class ISO8601Format
{
let format: ISO8601DateFormatter
init() {
let format = ISO8601DateFormatter()
format.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
format.timeZone = TimeZone(secondsFromGMT: 0)!
self.format = format
}
func date(from string: String) -> Date {
guard let date = format.date(from: string) else { fatalError() }
return date
}
func string(from date: Date) -> String { return format.string(from: date) }
}
class ISO8601Time
{
let date: Date
let format = ISO8601Format() //FIXME: Duplication
required init(date: Date) { self.date = date }
convenience init(string: String) {
let format = ISO8601Format() //FIXME: Duplication
let date = format.date(from: string)
self.init(date: date)
}
func concise() -> String { return format.string(from: date) }
func description() -> String { return date.description(with: .current) }
}
callsite
let now = Date()
let time1 = ISO8601Time(date: now)
print("time1.concise(): \(time1.concise())")
print("time1: \(time1.description())")
let time2 = ISO8601Time(string: "2020-03-24T23:16:17.661Z")
print("time2.concise(): \(time2.concise())")
print("time2: \(time2.description())")
My current code:
if let var timeResult = (jsonResult["dt"] as? Double) {
timeResult = NSDate().timeIntervalSince1970
println(timeResult)
println(NSDate())
}
The results:
println(timeResult) = 1415639000.67457
println(NSDate()) = 2014-11-10 17:03:20 +0000 was just to test to see what NSDate was providing.
I want the first to look like the last. The value for dt = 1415637900.
Also, how can I adjust to time zone? Running on iOS.
You can get a date with that value by using the NSDate(withTimeIntervalSince1970:) initializer:
let date = NSDate(timeIntervalSince1970: 1415637900)
To get the date to show as the current time zone I used the following.
if let timeResult = (jsonResult["dt"] as? Double) {
let date = NSDate(timeIntervalSince1970: timeResult)
let dateFormatter = NSDateFormatter()
dateFormatter.timeStyle = NSDateFormatterStyle.MediumStyle //Set time style
dateFormatter.dateStyle = NSDateFormatterStyle.MediumStyle //Set date style
dateFormatter.timeZone = NSTimeZone()
let localDate = dateFormatter.stringFromDate(date)
}
Swift 3.0 Version
if let timeResult = (jsonResult["dt"] as? Double) {
let date = Date(timeIntervalSince1970: timeResult)
let dateFormatter = DateFormatter()
dateFormatter.timeStyle = DateFormatter.Style.medium //Set time style
dateFormatter.dateStyle = DateFormatter.Style.medium //Set date style
dateFormatter.timeZone = self.timeZone
let localDate = dateFormatter.string(from: date)
}
Swift 5
if let timeResult = (jsonResult["dt"] as? Double) {
let date = Date(timeIntervalSince1970: timeResult)
let dateFormatter = DateFormatter()
dateFormatter.timeStyle = DateFormatter.Style.medium //Set time style
dateFormatter.dateStyle = DateFormatter.Style.medium //Set date style
dateFormatter.timeZone = .current
let localDate = dateFormatter.string(from: date)
}
It's simple to convert the Unix timestamp into the desired format. Lets suppose _ts is the Unix timestamp in long
let date = NSDate(timeIntervalSince1970: _ts)
let dayTimePeriodFormatter = NSDateFormatter()
dayTimePeriodFormatter.dateFormat = "MMM dd YYYY hh:mm a"
let dateString = dayTimePeriodFormatter.stringFromDate(date)
print( " _ts value is \(_ts)")
print( " _ts value is \(dateString)")
For managing dates in Swift 3 I ended up with this helper function:
extension Double {
func getDateStringFromUTC() -> String {
let date = Date(timeIntervalSince1970: self)
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_US")
dateFormatter.dateStyle = .medium
return dateFormatter.string(from: date)
}
}
This way it easy to use whenever you need it - in my case it was converting a string:
("1481721300" as! Double).getDateStringFromUTC() // "Dec 14, 2016"
Reference the DateFormatter docs for more details on formatting (Note that some of the examples are out of date)
I found this article to be very helpful as well
Here is a working Swift 3 solution from one of my apps.
/**
*
* Convert unix time to human readable time. Return empty string if unixtime
* argument is 0. Note that EMPTY_STRING = ""
*
* #param unixdate the time in unix format, e.g. 1482505225
* #param timezone the user's time zone, e.g. EST, PST
* #return the date and time converted into human readable String format
*
**/
private func getDate(unixdate: Int, timezone: String) -> String {
if unixdate == 0 {return EMPTY_STRING}
let date = NSDate(timeIntervalSince1970: TimeInterval(unixdate))
let dayTimePeriodFormatter = DateFormatter()
dayTimePeriodFormatter.dateFormat = "MMM dd YYYY hh:mm a"
dayTimePeriodFormatter.timeZone = NSTimeZone(name: timezone) as TimeZone!
let dateString = dayTimePeriodFormatter.string(from: date as Date)
return "Updated: \(dateString)"
}
func timeStringFromUnixTime(unixTime: Double) -> String {
let date = NSDate(timeIntervalSince1970: unixTime)
// Returns date formatted as 12 hour time.
dateFormatter.dateFormat = "hh:mm a"
return dateFormatter.stringFromDate(date)
}
func dayStringFromTime(unixTime: Double) -> String {
let date = NSDate(timeIntervalSince1970: unixTime)
dateFormatter.locale = NSLocale(localeIdentifier: NSLocale.currentLocale().localeIdentifier)
dateFormatter.dateFormat = "EEEE"
return dateFormatter.stringFromDate(date)
}
In Swift 5
Using this implementation you just have to give epoch time as a parameter and you will the output as (1 second ago, 2 minutes ago, and so on).
func setTimestamp(epochTime: String) -> String {
let currentDate = Date()
let epochDate = Date(timeIntervalSince1970: TimeInterval(epochTime) as! TimeInterval)
let calendar = Calendar.current
let currentDay = calendar.component(.day, from: currentDate)
let currentHour = calendar.component(.hour, from: currentDate)
let currentMinutes = calendar.component(.minute, from: currentDate)
let currentSeconds = calendar.component(.second, from: currentDate)
let epochDay = calendar.component(.day, from: epochDate)
let epochMonth = calendar.component(.month, from: epochDate)
let epochYear = calendar.component(.year, from: epochDate)
let epochHour = calendar.component(.hour, from: epochDate)
let epochMinutes = calendar.component(.minute, from: epochDate)
let epochSeconds = calendar.component(.second, from: epochDate)
if (currentDay - epochDay < 30) {
if (currentDay == epochDay) {
if (currentHour - epochHour == 0) {
if (currentMinutes - epochMinutes == 0) {
if (currentSeconds - epochSeconds <= 1) {
return String(currentSeconds - epochSeconds) + " second ago"
} else {
return String(currentSeconds - epochSeconds) + " seconds ago"
}
} else if (currentMinutes - epochMinutes <= 1) {
return String(currentMinutes - epochMinutes) + " minute ago"
} else {
return String(currentMinutes - epochMinutes) + " minutes ago"
}
} else if (currentHour - epochHour <= 1) {
return String(currentHour - epochHour) + " hour ago"
} else {
return String(currentHour - epochHour) + " hours ago"
}
} else if (currentDay - epochDay <= 1) {
return String(currentDay - epochDay) + " day ago"
} else {
return String(currentDay - epochDay) + " days ago"
}
} else {
return String(epochDay) + " " + getMonthNameFromInt(month: epochMonth) + " " + String(epochYear)
}
}
func getMonthNameFromInt(month: Int) -> String {
switch month {
case 1:
return "Jan"
case 2:
return "Feb"
case 3:
return "Mar"
case 4:
return "Apr"
case 5:
return "May"
case 6:
return "Jun"
case 7:
return "Jul"
case 8:
return "Aug"
case 9:
return "Sept"
case 10:
return "Oct"
case 11:
return "Nov"
case 12:
return "Dec"
default:
return ""
}
}
How to call?
setTimestamp(epochTime: time) and you'll get the desired output as a string.
Convert timestamp into Date object.
If timestamp object is invalid then return current date.
class func toDate(_ timestamp: Any?) -> Date? {
if let any = timestamp {
if let str = any as? NSString {
return Date(timeIntervalSince1970: str.doubleValue)
} else if let str = any as? NSNumber {
return Date(timeIntervalSince1970: str.doubleValue)
}
}
return nil
}
Swift:
extension Double {
func getDateStringFromUnixTime(dateStyle: DateFormatter.Style, timeStyle: DateFormatter.Style) -> String {
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = dateStyle
dateFormatter.timeStyle = timeStyle
return dateFormatter.string(from: Date(timeIntervalSince1970: self))
}
}
Anyway #Nate Cook's answer is accepted but I would like to improve it with better date format.
with Swift 2.2, I can get desired formatted date
//TimeStamp
let timeInterval = 1415639000.67457
print("time interval is \(timeInterval)")
//Convert to Date
let date = NSDate(timeIntervalSince1970: timeInterval)
//Date formatting
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "dd, MMMM yyyy HH:mm:a"
dateFormatter.timeZone = NSTimeZone(name: "UTC")
let dateString = dateFormatter.stringFromDate(date)
print("formatted date is = \(dateString)")
the result is
time interval is 1415639000.67457
formatted date is = 10, November 2014 17:03:PM
If you are maximizing the Codable protocol for parsing your JSON data. You could simply make the data type of dt as Date and do:
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .secondsSince1970
For me: Converting timestamps coming from API to a valid date :
`let date = NSDate.init(fromUnixTimestampNumber: timesTamp /* i.e 1547398524000 */) as Date?`
By using this code you will be able to convert timeStamp to Time and Date
let timeStamp = Date().timeIntervalSince1970
let date = NSDate(timeIntervalSince1970: timeStamp)
let dayTimePeriodFormatter = DateFormatter()
dayTimePeriodFormatter.dateFormat = "dd MMMM,YYYY.hh:mm a"
let dateTimeString = dayTimePeriodFormatter.string(from: date as Date)
let dateTime = dateTimeString.split(separator: ".")
print( "Date = \(dateTime[0])")
print( "Time = \(dateTime[1])")
Output:
Date = 19 January,2022
Time = 10:46 AM
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 an ISO 8601 date on 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))
Swift 4 • iOS 11.2.1 or later
extension ISO8601DateFormatter {
convenience init(_ formatOptions: Options) {
self.init()
self.formatOptions = formatOptions
}
}
extension Formatter {
static let iso8601withFractionalSeconds = ISO8601DateFormatter([.withInternetDateTime, .withFractionalSeconds])
}
extension Date {
var iso8601withFractionalSeconds: String { return Formatter.iso8601withFractionalSeconds.string(from: self) }
}
extension String {
var iso8601withFractionalSeconds: Date? { return Formatter.iso8601withFractionalSeconds.date(from: self) }
}
Usage:
Date().description(with: .current) // Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
let dateString = Date().iso8601withFractionalSeconds // "2019-02-06T00:35:01.746Z"
if let date = dateString.iso8601withFractionalSeconds {
date.description(with: .current) // "Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
print(date.iso8601withFractionalSeconds) // "2019-02-06T00:35:01.746Z\n"
}
iOS 9 • Swift 3 or later
extension Formatter {
static let iso8601withFractionalSeconds: 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
}()
}
Codable Protocol
If you need to encode and decode this format when working with Codable
protocol you can create your own custom date encoding/decoding strategies:
extension JSONDecoder.DateDecodingStrategy {
static let iso8601withFractionalSeconds = custom {
let container = try $0.singleValueContainer()
let string = try container.decode(String.self)
guard let date = Formatter.iso8601withFractionalSeconds.date(from: string) else {
throw DecodingError.dataCorruptedError(in: container,
debugDescription: "Invalid date: " + string)
}
return date
}
}
and the encoding strategy
extension JSONEncoder.DateEncodingStrategy {
static let iso8601withFractionalSeconds = custom {
var container = $1.singleValueContainer()
try container.encode(Formatter.iso8601withFractionalSeconds.string(from: $0))
}
}
Playground Testing
let dates = [Date()] // ["Feb 8, 2019 at 9:48 PM"]
encoding
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601withFractionalSeconds
let data = try! encoder.encode(dates)
print(String(data: data, encoding: .utf8)!)
decoding
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601withFractionalSeconds
let decodedDates = try! decoder.decode([Date].self, from: data) // ["Feb 8, 2019 at 9:48 PM"]
Remember to set the locale to en_US_POSIX as described in Technical Q&A1480. In Swift 3:
let date = Date()
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ"
print(formatter.string(from: date))
The issue is that if you're on a device which is using a non-Gregorian calendar, the year will not conform to RFC3339/ISO8601 unless you specify the locale as well as the timeZone and dateFormat string.
Or you can use ISO8601DateFormatter to get you out of the weeds of setting locale and timeZone yourself:
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))
For Swift 2 rendition, see previous revision of this answer.
If you want to use the ISO8601DateFormatter() with a date from a Rails 4+ JSON feed (and don't need millis of course), you need to set a few options on the formatter for it to work right otherwise the the date(from: string) function will return nil. Here's what I'm using:
extension Date {
init(dateString:String) {
self = Date.iso8601Formatter.date(from: dateString)!
}
static let iso8601Formatter: ISO8601DateFormatter = {
let formatter = ISO8601DateFormatter()
formatter.formatOptions = [.withFullDate,
.withTime,
.withDashSeparatorInDate,
.withColonSeparatorInTime]
return formatter
}()
}
Here's the result of using the options versus not in a playground screenshot:
Swift 5
If you're targeting iOS 11.0+ / macOS 10.13+, you simply use ISO8601DateFormatter with the withInternetDateTime and withFractionalSeconds options, like so:
let date = Date()
let iso8601DateFormatter = ISO8601DateFormatter()
iso8601DateFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
let string = iso8601DateFormatter.string(from: date)
// string looks like "2020-03-04T21:39:02.112Z"
To further compliment Andrés Torres Marroquín and Leo Dabus, I have a version that preserves fractional seconds. I can't find it documented anywhere, but Apple truncate fractional seconds to the microsecond (3 digits of precision) on both input and output (even though specified using SSSSSSS, contrary to Unicode tr35-31).
I should stress that this is probably not necessary for most use cases. Dates online do not typically need millisecond precision, and when they do, it is often better to use a different data format. But sometimes one must interoperate with a pre-existing system in a particular way.
Xcode 8/9 and Swift 3.0-3.2
extension Date {
struct Formatter {
static let iso8601: DateFormatter = {
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: .iso8601)
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(identifier: "UTC")
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSXXXXX"
return formatter
}()
}
var iso8601: String {
// create base Date format
var formatted = DateFormatter.iso8601.string(from: self)
// Apple returns millisecond precision. find the range of the decimal portion
if let fractionStart = formatted.range(of: "."),
let fractionEnd = formatted.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: formatted.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
// replace the decimal range with our own 6 digit fraction output
let microseconds = self.timeIntervalSince1970 - floor(self.timeIntervalSince1970)
var microsecondsStr = String(format: "%.06f", microseconds)
microsecondsStr.remove(at: microsecondsStr.startIndex)
formatted.replaceSubrange(fractionRange, with: microsecondsStr)
}
return formatted
}
}
extension String {
var dateFromISO8601: Date? {
guard let parsedDate = Date.Formatter.iso8601.date(from: self) else {
return nil
}
var preliminaryDate = Date(timeIntervalSinceReferenceDate: floor(parsedDate.timeIntervalSinceReferenceDate))
if let fractionStart = self.range(of: "."),
let fractionEnd = self.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: self.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
let fractionStr = self.substring(with: fractionRange)
if var fraction = Double(fractionStr) {
fraction = Double(floor(1000000*fraction)/1000000)
preliminaryDate.addTimeInterval(fraction)
}
}
return preliminaryDate
}
}
Uses ISO8601DateFormatter on iOS10 or newer.
Uses DateFormatter on iOS9 or older.
Swift 4
protocol DateFormatterProtocol {
func string(from date: Date) -> String
func date(from string: String) -> Date?
}
extension DateFormatter: DateFormatterProtocol {}
#available(iOS 10.0, *)
extension ISO8601DateFormatter: DateFormatterProtocol {}
struct DateFormatterShared {
static let iso8601: DateFormatterProtocol = {
if #available(iOS 10, *) {
return ISO8601DateFormatter()
} else {
// iOS 9
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
}
}()
}
In my case I have to convert the DynamoDB - lastUpdated column (Unix Timestamp) to Normal Time.
The initial value of lastUpdated was : 1460650607601 - converted down to 2016-04-14 16:16:47 +0000 via :
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)
}
In the future the format might need to be changed which could be a small head ache having date.dateFromISO8601 calls everywhere in an app. Use a class and protocol to wrap the implementation, changing the date time format call in one place will be simpler. Use RFC3339 if possible, its a more complete representation. DateFormatProtocol and DateFormat is great for dependency injection.
class AppDelegate: UIResponder, UIApplicationDelegate {
internal static let rfc3339DateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
internal static let localeEnUsPosix = "en_US_POSIX"
}
import Foundation
protocol DateFormatProtocol {
func format(date: NSDate) -> String
func parse(date: String) -> NSDate?
}
import Foundation
class DateFormat: DateFormatProtocol {
func format(date: NSDate) -> String {
return date.rfc3339
}
func parse(date: String) -> NSDate? {
return date.rfc3339
}
}
extension NSDate {
struct Formatter {
static let rfc3339: NSDateFormatter = {
let formatter = NSDateFormatter()
formatter.calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierISO8601)
formatter.locale = NSLocale(localeIdentifier: AppDelegate.localeEnUsPosix)
formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
formatter.dateFormat = rfc3339DateFormat
return formatter
}()
}
var rfc3339: String { return Formatter.rfc3339.stringFromDate(self) }
}
extension String {
var rfc3339: NSDate? {
return NSDate.Formatter.rfc3339.dateFromString(self)
}
}
class DependencyService: DependencyServiceProtocol {
private var dateFormat: DateFormatProtocol?
func setDateFormat(dateFormat: DateFormatProtocol) {
self.dateFormat = dateFormat
}
func getDateFormat() -> DateFormatProtocol {
if let dateFormatObject = dateFormat {
return dateFormatObject
} else {
let dateFormatObject = DateFormat()
dateFormat = dateFormatObject
return dateFormatObject
}
}
}
There is a new ISO8601DateFormatter class that let's you create a string with just one line. For backwards compatibility I used an old C-library. I hope this is useful for someone.
Swift 3.0
extension Date {
var iso8601: String {
if #available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *) {
return ISO8601DateFormatter.string(from: self, timeZone: TimeZone.current, formatOptions: .withInternetDateTime)
} else {
var buffer = [CChar](repeating: 0, count: 25)
var time = time_t(self.timeIntervalSince1970)
strftime_l(&buffer, buffer.count, "%FT%T%z", localtime(&time), nil)
return String(cString: buffer)
}
}
}
To complement the version of Leo Dabus, I added support for projects written Swift and Objective-C, also added support for the optional milliseconds, probably isn't the best but you would get the point:
Xcode 8 and Swift 3
extension Date {
struct 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
}()
}
var iso8601: String {
return Formatter.iso8601.string(from: self)
}
}
extension String {
var dateFromISO8601: Date? {
var data = self
if self.range(of: ".") == nil {
// Case where the string doesn't contain the optional milliseconds
data = data.replacingOccurrences(of: "Z", with: ".000000Z")
}
return Date.Formatter.iso8601.date(from: data)
}
}
extension NSString {
var dateFromISO8601: Date? {
return (self as String).dateFromISO8601
}
}
It is now 2022, but I was looking for an answer to this (i.e. how to convert a Date to ISO8601 that includes fractions of seconds). It turns out the answer nowadays is a one-liner:
var somedate: Date = Date.now
var isodate = somedate.ISO8601Format(Date.ISO8601FormatStyle(includingFractionalSeconds: true))
so this will print something like 2022-08-16T17:45:08.548Z
Without some manual String masks or TimeFormatters
import Foundation
struct DateISO: Codable {
var date: Date
}
extension Date{
var isoString: String {
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601
guard let data = try? encoder.encode(DateISO(date: self)),
let json = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: String]
else { return "" }
return json?.first?.value ?? ""
}
}
let dateString = Date().isoString
Based on the acceptable answer in an object paradigm
class ISO8601Format
{
let format: ISO8601DateFormatter
init() {
let format = ISO8601DateFormatter()
format.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
format.timeZone = TimeZone(secondsFromGMT: 0)!
self.format = format
}
func date(from string: String) -> Date {
guard let date = format.date(from: string) else { fatalError() }
return date
}
func string(from date: Date) -> String { return format.string(from: date) }
}
class ISO8601Time
{
let date: Date
let format = ISO8601Format() //FIXME: Duplication
required init(date: Date) { self.date = date }
convenience init(string: String) {
let format = ISO8601Format() //FIXME: Duplication
let date = format.date(from: string)
self.init(date: date)
}
func concise() -> String { return format.string(from: date) }
func description() -> String { return date.description(with: .current) }
}
callsite
let now = Date()
let time1 = ISO8601Time(date: now)
print("time1.concise(): \(time1.concise())")
print("time1: \(time1.description())")
let time2 = ISO8601Time(string: "2020-03-24T23:16:17.661Z")
print("time2.concise(): \(time2.concise())")
print("time2: \(time2.description())")
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 an ISO 8601 date on 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))
Swift 4 • iOS 11.2.1 or later
extension ISO8601DateFormatter {
convenience init(_ formatOptions: Options) {
self.init()
self.formatOptions = formatOptions
}
}
extension Formatter {
static let iso8601withFractionalSeconds = ISO8601DateFormatter([.withInternetDateTime, .withFractionalSeconds])
}
extension Date {
var iso8601withFractionalSeconds: String { return Formatter.iso8601withFractionalSeconds.string(from: self) }
}
extension String {
var iso8601withFractionalSeconds: Date? { return Formatter.iso8601withFractionalSeconds.date(from: self) }
}
Usage:
Date().description(with: .current) // Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
let dateString = Date().iso8601withFractionalSeconds // "2019-02-06T00:35:01.746Z"
if let date = dateString.iso8601withFractionalSeconds {
date.description(with: .current) // "Tuesday, February 5, 2019 at 10:35:01 PM Brasilia Summer Time"
print(date.iso8601withFractionalSeconds) // "2019-02-06T00:35:01.746Z\n"
}
iOS 9 • Swift 3 or later
extension Formatter {
static let iso8601withFractionalSeconds: 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
}()
}
Codable Protocol
If you need to encode and decode this format when working with Codable
protocol you can create your own custom date encoding/decoding strategies:
extension JSONDecoder.DateDecodingStrategy {
static let iso8601withFractionalSeconds = custom {
let container = try $0.singleValueContainer()
let string = try container.decode(String.self)
guard let date = Formatter.iso8601withFractionalSeconds.date(from: string) else {
throw DecodingError.dataCorruptedError(in: container,
debugDescription: "Invalid date: " + string)
}
return date
}
}
and the encoding strategy
extension JSONEncoder.DateEncodingStrategy {
static let iso8601withFractionalSeconds = custom {
var container = $1.singleValueContainer()
try container.encode(Formatter.iso8601withFractionalSeconds.string(from: $0))
}
}
Playground Testing
let dates = [Date()] // ["Feb 8, 2019 at 9:48 PM"]
encoding
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601withFractionalSeconds
let data = try! encoder.encode(dates)
print(String(data: data, encoding: .utf8)!)
decoding
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601withFractionalSeconds
let decodedDates = try! decoder.decode([Date].self, from: data) // ["Feb 8, 2019 at 9:48 PM"]
Remember to set the locale to en_US_POSIX as described in Technical Q&A1480. In Swift 3:
let date = Date()
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZZZZZ"
print(formatter.string(from: date))
The issue is that if you're on a device which is using a non-Gregorian calendar, the year will not conform to RFC3339/ISO8601 unless you specify the locale as well as the timeZone and dateFormat string.
Or you can use ISO8601DateFormatter to get you out of the weeds of setting locale and timeZone yourself:
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))
For Swift 2 rendition, see previous revision of this answer.
If you want to use the ISO8601DateFormatter() with a date from a Rails 4+ JSON feed (and don't need millis of course), you need to set a few options on the formatter for it to work right otherwise the the date(from: string) function will return nil. Here's what I'm using:
extension Date {
init(dateString:String) {
self = Date.iso8601Formatter.date(from: dateString)!
}
static let iso8601Formatter: ISO8601DateFormatter = {
let formatter = ISO8601DateFormatter()
formatter.formatOptions = [.withFullDate,
.withTime,
.withDashSeparatorInDate,
.withColonSeparatorInTime]
return formatter
}()
}
Here's the result of using the options versus not in a playground screenshot:
Swift 5
If you're targeting iOS 11.0+ / macOS 10.13+, you simply use ISO8601DateFormatter with the withInternetDateTime and withFractionalSeconds options, like so:
let date = Date()
let iso8601DateFormatter = ISO8601DateFormatter()
iso8601DateFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
let string = iso8601DateFormatter.string(from: date)
// string looks like "2020-03-04T21:39:02.112Z"
To further compliment Andrés Torres Marroquín and Leo Dabus, I have a version that preserves fractional seconds. I can't find it documented anywhere, but Apple truncate fractional seconds to the microsecond (3 digits of precision) on both input and output (even though specified using SSSSSSS, contrary to Unicode tr35-31).
I should stress that this is probably not necessary for most use cases. Dates online do not typically need millisecond precision, and when they do, it is often better to use a different data format. But sometimes one must interoperate with a pre-existing system in a particular way.
Xcode 8/9 and Swift 3.0-3.2
extension Date {
struct Formatter {
static let iso8601: DateFormatter = {
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: .iso8601)
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(identifier: "UTC")
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSXXXXX"
return formatter
}()
}
var iso8601: String {
// create base Date format
var formatted = DateFormatter.iso8601.string(from: self)
// Apple returns millisecond precision. find the range of the decimal portion
if let fractionStart = formatted.range(of: "."),
let fractionEnd = formatted.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: formatted.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
// replace the decimal range with our own 6 digit fraction output
let microseconds = self.timeIntervalSince1970 - floor(self.timeIntervalSince1970)
var microsecondsStr = String(format: "%.06f", microseconds)
microsecondsStr.remove(at: microsecondsStr.startIndex)
formatted.replaceSubrange(fractionRange, with: microsecondsStr)
}
return formatted
}
}
extension String {
var dateFromISO8601: Date? {
guard let parsedDate = Date.Formatter.iso8601.date(from: self) else {
return nil
}
var preliminaryDate = Date(timeIntervalSinceReferenceDate: floor(parsedDate.timeIntervalSinceReferenceDate))
if let fractionStart = self.range(of: "."),
let fractionEnd = self.index(fractionStart.lowerBound, offsetBy: 7, limitedBy: self.endIndex) {
let fractionRange = fractionStart.lowerBound..<fractionEnd
let fractionStr = self.substring(with: fractionRange)
if var fraction = Double(fractionStr) {
fraction = Double(floor(1000000*fraction)/1000000)
preliminaryDate.addTimeInterval(fraction)
}
}
return preliminaryDate
}
}
Uses ISO8601DateFormatter on iOS10 or newer.
Uses DateFormatter on iOS9 or older.
Swift 4
protocol DateFormatterProtocol {
func string(from date: Date) -> String
func date(from string: String) -> Date?
}
extension DateFormatter: DateFormatterProtocol {}
#available(iOS 10.0, *)
extension ISO8601DateFormatter: DateFormatterProtocol {}
struct DateFormatterShared {
static let iso8601: DateFormatterProtocol = {
if #available(iOS 10, *) {
return ISO8601DateFormatter()
} else {
// iOS 9
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
}
}()
}
In my case I have to convert the DynamoDB - lastUpdated column (Unix Timestamp) to Normal Time.
The initial value of lastUpdated was : 1460650607601 - converted down to 2016-04-14 16:16:47 +0000 via :
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)
}
In the future the format might need to be changed which could be a small head ache having date.dateFromISO8601 calls everywhere in an app. Use a class and protocol to wrap the implementation, changing the date time format call in one place will be simpler. Use RFC3339 if possible, its a more complete representation. DateFormatProtocol and DateFormat is great for dependency injection.
class AppDelegate: UIResponder, UIApplicationDelegate {
internal static let rfc3339DateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
internal static let localeEnUsPosix = "en_US_POSIX"
}
import Foundation
protocol DateFormatProtocol {
func format(date: NSDate) -> String
func parse(date: String) -> NSDate?
}
import Foundation
class DateFormat: DateFormatProtocol {
func format(date: NSDate) -> String {
return date.rfc3339
}
func parse(date: String) -> NSDate? {
return date.rfc3339
}
}
extension NSDate {
struct Formatter {
static let rfc3339: NSDateFormatter = {
let formatter = NSDateFormatter()
formatter.calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierISO8601)
formatter.locale = NSLocale(localeIdentifier: AppDelegate.localeEnUsPosix)
formatter.timeZone = NSTimeZone(forSecondsFromGMT: 0)
formatter.dateFormat = rfc3339DateFormat
return formatter
}()
}
var rfc3339: String { return Formatter.rfc3339.stringFromDate(self) }
}
extension String {
var rfc3339: NSDate? {
return NSDate.Formatter.rfc3339.dateFromString(self)
}
}
class DependencyService: DependencyServiceProtocol {
private var dateFormat: DateFormatProtocol?
func setDateFormat(dateFormat: DateFormatProtocol) {
self.dateFormat = dateFormat
}
func getDateFormat() -> DateFormatProtocol {
if let dateFormatObject = dateFormat {
return dateFormatObject
} else {
let dateFormatObject = DateFormat()
dateFormat = dateFormatObject
return dateFormatObject
}
}
}
There is a new ISO8601DateFormatter class that let's you create a string with just one line. For backwards compatibility I used an old C-library. I hope this is useful for someone.
Swift 3.0
extension Date {
var iso8601: String {
if #available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *) {
return ISO8601DateFormatter.string(from: self, timeZone: TimeZone.current, formatOptions: .withInternetDateTime)
} else {
var buffer = [CChar](repeating: 0, count: 25)
var time = time_t(self.timeIntervalSince1970)
strftime_l(&buffer, buffer.count, "%FT%T%z", localtime(&time), nil)
return String(cString: buffer)
}
}
}
To complement the version of Leo Dabus, I added support for projects written Swift and Objective-C, also added support for the optional milliseconds, probably isn't the best but you would get the point:
Xcode 8 and Swift 3
extension Date {
struct 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
}()
}
var iso8601: String {
return Formatter.iso8601.string(from: self)
}
}
extension String {
var dateFromISO8601: Date? {
var data = self
if self.range(of: ".") == nil {
// Case where the string doesn't contain the optional milliseconds
data = data.replacingOccurrences(of: "Z", with: ".000000Z")
}
return Date.Formatter.iso8601.date(from: data)
}
}
extension NSString {
var dateFromISO8601: Date? {
return (self as String).dateFromISO8601
}
}
It is now 2022, but I was looking for an answer to this (i.e. how to convert a Date to ISO8601 that includes fractions of seconds). It turns out the answer nowadays is a one-liner:
var somedate: Date = Date.now
var isodate = somedate.ISO8601Format(Date.ISO8601FormatStyle(includingFractionalSeconds: true))
so this will print something like 2022-08-16T17:45:08.548Z
Without some manual String masks or TimeFormatters
import Foundation
struct DateISO: Codable {
var date: Date
}
extension Date{
var isoString: String {
let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601
guard let data = try? encoder.encode(DateISO(date: self)),
let json = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: String]
else { return "" }
return json?.first?.value ?? ""
}
}
let dateString = Date().isoString
Based on the acceptable answer in an object paradigm
class ISO8601Format
{
let format: ISO8601DateFormatter
init() {
let format = ISO8601DateFormatter()
format.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
format.timeZone = TimeZone(secondsFromGMT: 0)!
self.format = format
}
func date(from string: String) -> Date {
guard let date = format.date(from: string) else { fatalError() }
return date
}
func string(from date: Date) -> String { return format.string(from: date) }
}
class ISO8601Time
{
let date: Date
let format = ISO8601Format() //FIXME: Duplication
required init(date: Date) { self.date = date }
convenience init(string: String) {
let format = ISO8601Format() //FIXME: Duplication
let date = format.date(from: string)
self.init(date: date)
}
func concise() -> String { return format.string(from: date) }
func description() -> String { return date.description(with: .current) }
}
callsite
let now = Date()
let time1 = ISO8601Time(date: now)
print("time1.concise(): \(time1.concise())")
print("time1: \(time1.description())")
let time2 = ISO8601Time(string: "2020-03-24T23:16:17.661Z")
print("time2.concise(): \(time2.concise())")
print("time2: \(time2.description())")