I bet this is simple. I'm trying in Xcode playgrounds to play with getting a string date
let string = "2022-11-27 00:00:00 +0000"
and converting that into a Date object that's formatted like DD-MM-YYYY
func airdateFormat(_ key: String) -> Date? {
let expectedFormat = Date().formatted(.dateTime.day().month(.wide).year())
let date = try! Date(strategy: expectedFormat)
return date
}
I also tried
func airdateFormat(_ key: String) -> Date? {
guard let dateString = self[key] as? String else { return nil }
let dateFormatted = DateFormatter.dateFormat(fromTemplate: "MM-DD-YYYY", options: Int, locale: Locale?)
return dateFormatted().date(from: dateString)
}
}
I'm parsing this Date string from json hence the guard/else statement
You need to use a format that matches your input to parse the string to a Date
If you want to use the DateFormatter
let string = "2022-11-27 12:34:56 +0000"
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss Z"
let date = formatter.date(from: string)
and for recent OS versions you use a FormatStyle
let formatStyle = Date.FormatStyle()
.year(.defaultDigits)
.month(.twoDigits)
.day(.twoDigits)
.hour()
.minute()
.second()
.timeZone()
let date = try formatStyle.parse(string)
Getting nil converting date string to date
func convertDateFormater(dateStr: ""2022-10-22T22:22:16:2216Z"") -> String? {
let inputFormatter = DateFormatter()
inputFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
let strSelected = inputFormatter.date(from: dateStr)
}
convertDateFormater(dateStr: "2022-10-23T00:00:00.000Z") // Working fine
***convertDateFormater(dateStr: ""2022-10-22T22:22:16:2216Z"") // Not Working fine getting nil***
Should work convertDateFormater(dateStr: ""2022-10-22T22:22:16:2216Z"")
There are many issues in this code
"" … "" is invalid syntax.
There is no parameter type defined.
Nothing – or even the wrong type – is returned.
Z is a format specifier, it must not be wrapped in single quotes.
Apart from that look at your date string. A colon between seconds and milliseconds is very uncommon but it works with this code
func convertDateFormater(dateStr: String) -> Date? {
let inputFormatter = DateFormatter()
inputFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss:SSSZ"
return inputFormatter.date(from: dateStr)
}
convertDateFormater(dateStr: "2022-10-22T22:22:16:2216Z")
But you cannot convert both strings (colon and period separator) with the same date format.
To do so you need a second parameter
func convertDateFormater(dateStr: String, hasColonMillisecondSeparator: Bool = false) -> Date? {
let inputFormatter = DateFormatter()
inputFormatter.dateFormat = hasColonMillisecondSeparator ? "yyyy-MM-dd'T'HH:mm:ss:SSSZ" : "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
return inputFormatter.date(from: dateStr)
}
convertDateFormater(dateStr: "2022-10-23T00:00:00.000Z")
convertDateFormater(dateStr: "2022-10-22T22:22:16:2216Z", hasColonMillisecondSeparator: true)
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())")
I'm hitting a webservice that is returning a string in the following format:
"yyyy-MM-dd'T'HH:mmZ"
It's very close to the standard UTC format, but just without the ss at the end. My issue is that my dateFormatter is always returning nil...and I have tried to make sure that locale and everything else is setup properly.
Here is an example of an actual string:
2019-12-26T00:00Z
Here is the code that creates the DF:
extension DateFormatter {
#objc static func defaultDateFormat(_ format: String) -> DateFormatter {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "US")
formatter.dateFormat = format
return formatter
}
func date(from string: String?) -> Date? {
if let string = string {
return self.date(from: string)
} else {
return nil
}
}
func string(fromOptional date: Date?) -> String? {
if let date = date {
return self.string(from: date)
} else {
return nil
}
}
func string(fromOptional date: Date?, defaultStr: String) -> String {
return self.string(fromOptional: date) ?? defaultStr
}
}
let df = DateFormatter.defaultDateFormat("yyyy-MM-dd'T'HH:mmZ")
let date: Date? = df.date(from: __dateString__) // always nil
A few observations:
You want to use a locale of en_US_POSIX, an invariant locale that always works for ISO 8601 / RFC 3339 date strings. See Technical Q&A 1480.
If you want to use this formatter to convert a date back to a string like 2019-12-26T00:00Z, you will want to:
Use X (or ZZZZZ or XXXXX) in your format string, not Z (see the “zone” section in the table at Date Format Patterns and you’ll see how these various time zone patterns, e.g. Z, ZZZZZ, and X, are interpreted); and
Set the timeZone of the formatter to use Zulu/GMT/UTC.
Thus:
#objc static func defaultDateFormat(_ format: String) -> DateFormatter {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = format
return formatter
}
And
let df = DateFormatter.defaultDateFormat("yyyy-MM-dd'T'HH:mmX")
let date = df.date(from: "2019-12-26T00:00Z")
Or
let string = df.string(from: Date())
I'm trying to make an attendance app and I am really confused about date and time in iOS and Firebase.
I use date as Key, this is the structure of my Firebase database.
--Employees
--Unique_ID
--Details
Name: John
--Attendance
--dateToday
Timein: 8:00 AM
Timeout: 5:00 PM
BreakStart: 12:00 PM
BreakFinish: 1:00 PM
This is my code to get the date timestamp I used as Key
override func viewDidLoad() {
super.viewDidLoad()
let now = NSDate()
let nowTimeStamp = self.getCurrentTimeStampWOMiliseconds(dateToConvert: now)
// I save this dateToday as Key in Firebase
dateToday = nowTimeStamp
}
func getCurrentTimeStampWOMiliseconds(dateToConvert: NSDate) -> String {
let objDateformat: DateFormatter = DateFormatter()
objDateformat.dateFormat = "yyyy-MM-dd"
let strTime: String = objDateformat.string(from: dateToConvert as Date)
let objUTCDate: NSDate = objDateformat.date(from: strTime)! as NSDate
let milliseconds: Int64 = Int64(objUTCDate.timeIntervalSince1970)
let strTimeStamp: String = "\(milliseconds)"
return strTimeStamp
}
But when I convert it back to date I get 2017-09-22 16:00:00 +0000, which is wrong because it is 23rd of September in my location.
What is the right code to use so that I can get the correct date timestamp and time timestamp?
For saving Current time to firebase database I use Unic Epoch Conversation:
let timestamp = NSDate().timeIntervalSince1970
and For Decoding Unix Epoch time to Date().
let myTimeInterval = TimeInterval(timestamp)
let time = NSDate(timeIntervalSince1970: TimeInterval(myTimeInterval))
If you just want the unix timestamp, create an extension:
extension Date {
func currentTimeMillis() -> Int64 {
return Int64(self.timeIntervalSince1970 * 1000)
}
}
Then you can use it just like in other programming languages:
let timestamp = Date().currentTimeMillis()
First I would recommend you to store your timestamp as a NSNumber in your Firebase Database, instead of storing it as a String.
Another thing worth mentioning here, is that if you want to manipulate dates with Swift, you'd better use Date instead of NSDate, except if you're interacting with some Obj-C code in your app.
You can of course use both, but the Documentation states:
Date bridges to the NSDate class. You can use these interchangeably in
code that interacts with Objective-C APIs.
Now to answer your question, I think the problem here is because of the timezone.
For example if you print(Date()), as for now, you would get:
2017-09-23 06:59:34 +0000
This is the Greenwich Mean Time (GMT).
So depending on where you are located (or where your users are located) you need to adjust the timezone before (or after, when you try to access the data for example) storing your Date:
let now = Date()
let formatter = DateFormatter()
formatter.timeZone = TimeZone.current
formatter.dateFormat = "yyyy-MM-dd HH:mm"
let dateString = formatter.string(from: now)
Then you have your properly formatted String, reflecting the current time at your location, and you're free to do whatever you want with it :) (convert it to a Date / NSNumber, or store it directly as a String in the database..)
in Swift 5
extension Date {
static var currentTimeStamp: Int64{
return Int64(Date().timeIntervalSince1970 * 1000)
}
}
call like this:
let timeStamp = Date.currentTimeStamp
print(timeStamp)
Thanks #lenooh
The simple way to create Current TimeStamp. like below,
func generateCurrentTimeStamp () -> String {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy_MM_dd_hh_mm_ss"
return (formatter.string(from: Date()) as NSString) as String
}
you can call like this:
let timeStmp = generateCurrentTimeStamp()
print("time stamp: \(timeStmp)")
If you code for iOS 13.0 or later and want a timestamp, then you can use:
let currentDate = NSDate.now
On expanding #MacacoAzul's answer here is my current working example :
import SwiftUI
struct TimestampDemo: View {
var body: some View {
Text(getActualTimeStamp(1))
.padding(10)
Text(getActualTimeStamp(2))
.padding(10)
Text(getActualTimeStamp(3))
.padding(10)
Text(getActualTimeStamp(4))
.padding(10)
}
func getActualTimeStamp(_ tipo:Int) -> String {
let date = Date()
let formatter = DateFormatter()
if tipo == 1{
formatter.dateFormat = "dd/MM/yyyy"
} else if tipo == 2{
formatter.dateFormat = "yyyy-MM-dd HH:mm"
}else if tipo == 3{
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
}
else if tipo == 4 {
formatter.dateFormat = "dd-MM-yyyy"
}
return formatter.string(from: date)
}
}
struct TimestampDemo_Previews: PreviewProvider {
static var previews: some View {
TimestampDemo()
}
}
Swift Language Version : 5
When we convert a UTC timestamp (2017-11-06 20:15:33 -08:00) into a Date object, the time zone is zeroed out to GMT. For calculating time intervals, this isn't an issue, but it can be for rendering times in the UI.
I favor the RFC3339 format (2017-11-06T20:15:33-08:00) for its universality. The date format in Swift is yyyy-MM-dd'T'HH:mm:ssXXXXX but RFC3339 allows us to take advantage of the ISO8601DateFormatter:
func getDateFromUTC(RFC3339: String) -> Date? {
let formatter = ISO8601DateFormatter()
return formatter.date(from: RFC3339)
}
RFC3339 also makes time-zone extraction simple:
func getTimeZoneFromUTC(RFC3339: String) -> TimeZone? {
switch RFC3339.suffix(6) {
case "+05:30":
return TimeZone(identifier: "Asia/Kolkata")
case "+05:45":
return TimeZone(identifier: "Asia/Kathmandu")
default:
return nil
}
}
There are 37 or so other time zones we'd have to account for and it's up to you to determine which ones, because there is no definitive list. Some standards count fewer time zones, some more. Most time zones break on the hour, some on the half hour, some on 0:45, some on 0:15.
We can combine the two methods above into something like this:
func getFormattedDateFromUTC(RFC3339: String) -> String? {
guard let date = getDateFromUTC(RFC3339: RFC3339),
let timeZone = getTimeZoneFromUTC(RFC3339: RFC3339) else {
return nil
}
let formatter = DateFormatter()
formatter.dateFormat = "h:mma EEE, MMM d yyyy"
formatter.amSymbol = "AM"
formatter.pmSymbol = "PM"
formatter.timeZone = timeZone // preserve local time zone
return formatter.string(from: date)
}
And so the string "2018-11-06T17:00:00+05:45", which represents 5:00PM somewhere in Kathmandu, will print 5:00PM Tue, Nov 6 2018, displaying the local time, regardless of where the machine is.
As an aside, I recommend storing dates as strings remotely (including Firestore which has a native date object) because, I think, remote data should agnostic to create as little friction between servers and clients as possible.
you can even create a function to return different time stamps depending on your necessity:
func dataatual(_ tipo:Int) -> String {
let date = Date()
let formatter = DateFormatter()
if tipo == 1{
formatter.dateFormat = "dd/MM/yyyy"
} else if tipo == 2{
formatter.dateFormat = "yyyy-MM-dd HH:mm"
} else {
formatter.dateFormat = "dd-MM-yyyy"
}
return formatter.string(from: date)
}