I need to check to see if the current date is during daylight savings time. In pseudocode that would be like this:
let date = NSDate()
if date.isDaylightSavingsTime {
print("Success")
}
I haven't been able to find the solution to this anywhere on the internet.
An NSDate alone represents an absolute point in time.
To decide if a date is during daylight savings time or not
it needs to be interpreted in the context of a time zone.
Therefore you'll find that method in the NSTimeZone class and not
in the NSDate class. Example:
let date = NSDate()
let tz = NSTimeZone.localTimeZone()
if tz.isDaylightSavingTimeForDate(date) {
}
Update for Swift 3/4:
let date = Date()
let tz = TimeZone.current
if tz.isDaylightSavingTime(for: date) {
print("Summertime, and the livin' is easy ... 🎶")
}
Swift 4.0 or later
You can check a date isDaylightSavingTime in two ways by time zone identifier or abbreviation.
let timeZone = TimeZone(identifier: "America/New_York")!
if timeZone.isDaylightSavingTime(for: Date()) {
print("Yes, daylight saving time at a given date")
}
let timeZone = TimeZone(abbreviation: "EST")!
if timeZone.isDaylightSavingTime(for: Date()) {
print("Yes, daylight saving time at a given date")
}
Related
I need to convert the UTC time to PST
From backed, I get UTC dates like "2021-06-25T07:00:00Z"
I need to show the dates in Hstack from Provided UTC date to the current date.
I write the following code.
Anyone help to me.
func datesRange(from:Date, to:Date)->[Date]{
if from > to {return [Date]()}
var tmpdate = from
var array:[Date] = []
while tmpdate <= to {
array.append(tmpdate)
tmpdate = Calendar.current.date(byAdding: .day,value: 1, to: tmpdate)!
}
return array
}
extension Date{
func convertTimezone(timezone:String)-> Date{
if let targettimeZone = TimeZone(abbreviation: timezone){
let delta = TimeInterval(targettimeZone.secondsFromGMT(for: self) - TimeZone.current.secondsFromGMT(for: self))
return addingTimeInterval(delta)
}else{
return self
}
}
}
I used as follows
func getrangeDays(){
let startday = "2021-06-25T07:00:00Z"
let dateformater = DateFormatter()
dateformater.locale = Locale(identifier: "en_US_POSIX")
dateformater.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
if let date = dateformater.date(from: startday){
let rangedays = datesRange(from:date.convertTimezone(timezone: "PST") , to: Date().convertTimezone(timezone: "PST"))
print(rangedays)
}
}
Your convertTimezone() function does not make sense. It is trying to convert a Date to a different time zone. A Date object does not have a time zone. It is an instant in time, anywhere on the planet. Time zones only make sense when you want to display a Date, or do time zone specific date calculations. (And in that case you want to create a Calendar object and set its time zone to the desired time zone, then use that Calendar for your date calculations.)
Get rid of that function.
Convert your input date string to a Date as you are doing now (although you might want to use an ISO8601DateFormatter rather than a regular date formatter, since those are specifically intended for handling ISO8601 dates.)
Build your date range using your datesRange() function.
Then use a second DateFormatter to display your dates in PST. (Not convert Dates to PST. That doesn't make sense.)
What do we got: Date+time (format yyyy-mm-dd hh:mm a)
What are we looking for: Time difference in minutes
What operation: NewDate - OldDate
So, I wonder how I could accomplish above goal? I would like to format the date and time to US, regardless from which locale the user has. How can I do that?
Then I will save the 'oldTime' into UserDefaults, and use it for later calculation. The goal is to put the user on delay for 5 minutes and the calculations will be performed to determine if user should be on delay or not.
Just make a function that takes two dates and compares them like this.
import UIKit
func minutesBetweenDates(_ oldDate: Date, _ newDate: Date) -> CGFloat {
//get both times sinces refrenced date and divide by 60 to get minutes
let newDateMinutes = newDate.timeIntervalSinceReferenceDate/60
let oldDateMinutes = oldDate.timeIntervalSinceReferenceDate/60
//then return the difference
return CGFloat(newDateMinutes - oldDateMinutes)
}
//Usage:
let myDateFormatter = DateFormatter()
myDateFormatter.dateFormat = "yyyy-MM-dd HH:mm"
//You'll need both dates to compare, you can get them by just storing a Date object when you first start the timer.
//Then when you need to check it, compare it to Date()
let oldDate: Date = myDateFormatter.date(from: String("2019-06-22 11:25"))
func validateRefresh() {
//do the comparison between the old date and the now date like this.
if minutesBetweenDates(oldDate, Date()) > 5 {
//Do whatever
}
}
You can, of course, change the .dateFormat value on the date formatter to be whatever format you'd like. A great website for finding the right format is: https://nsdateformatter.com/.
You say:
I would like to format the date and time to US, regardless from which locale the user has. How can I do that?
Specify a Locale of en_US_POSIX:
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd hh:mm a"
formatter.locale = Locale(identifier: "en_US_POSIX")
The locale is not the only question.
There’s also a timezone question. For example, you're driving out of Chicago and go from Central to Eastern timezones; do you really want to consider that one hour has passed?
Do you really want to discard seconds? If you do that, the 59 seconds between going from 8:00:00pm to 8:00:59pm will be considered “zero minutes” but the one second between 8:00:59pm and 8:01:00pm will be considered “one minute”.
Frankly, if I wanted to save a locale and timezone invariant date string, I’d suggest using ISO8601DateFormatter.
Then I will save the 'oldTime' into UserDefaults, and use it for later calculation.
If that’s why you’re using this DateFormatter, I’d suggest saving the Date object directly.
UserDefaults.standard.set(oldTime, forKey: "oldTime")
And to retrieve it:
if let oldTime = UserDefaults.standard.object(forKey: "oldTime") as? Date {
...
}
In terms of calculating the number of minutes between two Date objects
let minutes = Calendar.current
.dateComponents([.minute], from: date1, to: date2)
.minute
If you want the number of seconds, you can also use timeIntervalSince:
let seconds = date2.timeIntervalSince(date1)
And if you wanted to show the amount of elapsed time as a nice localized string:
let intervalFormatter = DateComponentsFormatter()
intervalFormatter.allowedUnits = [.minute, .second]
intervalFormatter.unitsStyle = .full
let string = intervalFormatter.string(from: date1, to: date2)
I'm not convinced that your question is the best way to go about accomplishing your aim, but the code below will work.
let dateFormatterNow = DateFormatter()
dateFormatterNow.dateFormat = "yyyy-MM-dd hh:mm a"
dateFormatterNow.timeZone = TimeZone(abbreviation: "EST")
let oldDateString = "2019-06-23 12:44 p"
let oldDate = dateFormatterNow.date(from: oldDateString)
let newDateString = "2019-06-23 12:54 p"
let newDate = dateFormatterNow.date(from: newDateString)
if let oldDate = oldDate, let newDate = newDate {
let diffInMins = Calendar.current.dateComponents([.minute], from: oldDate, to: newDate).minute
print(diffInMins)
}
hi I want to get current hour and minute from Date(), so I need to format it into string and want to bring back into date again. But after I try to convert to date the year change into 2000, how can I got back to current year.
//date formatter
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"
dateFormatter.timeZone = TimeZone.current
// Get current time and format it to compare
var currentTime = Date() //Get current time
let currentTimeStr = dateFormatter.string(from: currentTime) //get current time only hour and minute
currentTime = dateFormatter.date(from: currentTimeStr)! //this is where the problem because the year change into 1 January 2000
From what I read in the comments, I think you want both the current time in a Date object and also a string with only hours and minutes in "HH:MM" format.
The problem comes from trying to use a formatter that doesn't have a year specified. You are overwriting the currentTime from a string that doesn't have a year (or day, or month) defined, so it defaults to Jan 1st 2000 (the hours and minutes should be correct).
You're also saying you need to format it into a String, and then go back to a Date object. You don't, you already have all the data you need in the Date object, so keep it around and use it when you need to. If this means creating a bunch of DateFormatters all over your project, you can always extend Date to have a function or variable that returns the string with the format you want.
extension Date {
var hoursAndMinutesString: String {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"
dateFormatter.timeZone = TimeZone.current
return dateFormatter.string(from: self)
}
}
Then just call the function from the Date object when you need to, like this:
currentTime.hoursAndMinutesString
I have the following string:
let dateString = "2018-04-18T04:54:00-04:00"
I initialize a Date via the ISO8601DateForamtter by doing the following:
let formatter = ISO8601DateFormatter()
let date = formatter.date(from: dateString)
If I print the date, I get the following:
Apr 18, 2018 at 1:54am
The formatter is automatically converting the time into my local time. How can I prevent accounting for my time zone? For example, I want the Date object to show the following instead:
Apr 18, 2018 at 4:54am
With ISO8601, 2018-04-18T04:54:00-04:00 means 2018-04-18 04:54:00 in GMT -4h. To print the time as it is in the original string, you need to create a date formatter with the specific time zone which is -4.
let dateFormatter = DateFormatter()
dateFormatter.timeZone = TimeZone(secondsFromGMT: -4 * 60 * 60)
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
print(dateFormatter.string(from: date))
You will get
2018-04-17 04:54:00
FYI, I'm adding a link for ISO8601
You need to parse the timezone from your date string and use it to set the timezone from your date formatter:
func secondsFromGMT(from string: String) -> Int {
guard !string.hasSuffix("Z") else { return 0 }
let timeZone = string.suffix(6)
let comps = timeZone.components(separatedBy: ":")
guard let hours = comps.first,
let minutes = comps.last,
let hr = Int(hours),
let min = Int(minutes) else { return 0 }
return hr * 3600 + min * 60
}
let dateString = "2018-04-18T04:54:00-04:00"
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssxxxxx"
formatter.locale = Locale(identifier: "en_US_POSIX")
if let dateFromString = formatter.date(from: dateString) {
formatter.timeZone = TimeZone(secondsFromGMT: secondsFromGMT(from: dateString))
formatter.dateFormat = "MMM dd, yyyy 'at' h:mma"
formatter.amSymbol = "am"
formatter.pmSymbol = "pm"
print(formatter.string(from: dateFromString)) // Apr 18, 2018 at 4:54am
}
Instead of logging the Date directly, have a look at the string(from:timeZone:formatOptions:) method on ISO8601DateFormatter. With this, you should be able to get a date string for any time zone you desire.
You should set your formatter to the appropriate timezone such as (UTC example below):
formatter.timeZone = TimeZone(identifier: "UTC")
or alternatively specify against GMT:
formatter.timeZone = TimeZone(secondsFromGMT: 0)
The date that you are receiving from your current formatter is technically correct. Setting the date backwards as described in the currently accepted answer is not advised because you are effectively hard-coding an intended time zone. As soon as your device enters another time zone (or if a user downloads your app outside of the current time zone), your information will be incorrect.
If you are trying to display this time in the UTC time zone, you need to use another formatter to correctly format the output in the target time zone.
let utcFormatter = DateFormatter()
utcFormatter.timeZone = TimeZone(secondsFromGMT: 0)
// Perform any other transformations you'd like
let output = utcFormatter.string(from: date)
But why is your original date correct?
The Date API is incredibly robust and doing a lot of things under-the-hood, but is effectively implemented using a simple Double. The automaic time-zone information that it's displaying to you is an abstraction to make it easier to reason about. A date technically has no knowledge of what time zone it's in – but converting it to a string implicitly applies an inferred date formatter on the date and returns information it thinks will be most useful to you.
If you're doing manipulations on a date, you're likely using the Calendar API. You typically get a new instance from using Calendar.current, which will create a new calendar with your current time zone information. You can change the represented time zone of the calendar like this:
var calendar = Calendar.current
calendar.timeZone = TimeZone(secondsFromGMT: 0)
This will give you relative dates that will work in any time zone without modifying the base Date object that you're working with.
I want to convert dateStartString = “28/02/2018” in to Date and compare that converted date with today date. when i convert dateStartString the converted date is "2018-02-27 18:30:00 UTC".why its output is wrong date?
here is my code
var dateStartString = "28/02/2018"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy"
guard let dateStartDate = dateFormatter.date(from: dateStartString) else {
fatalError("ERROR: Date conversion failed due to mismatched format.")
}
let dateToday = Date()
if(dateStartDate>=dateToday){
print("Yes")
}
else{
print("Today date is 28/02/2018. Why it print No?")
}
Hope you understand my problem.
Thanks in advance.
You need to understand that Date does not only represent a date, but also a time.
>= compares both date and time components of a Date object. Since you didn't specified any time in your date string, the API assumed it to be 00:00:00 in your local time, which is 18:30:00 of the previous day in UTC. Why UTC, you ask? That's what the description of the date always is. When you print a date, it always prints it in UTC time. To print it in your time zone, set the timeZone property of your date formatter and format it.
One way to only compare the date components is by removing the time components. From this answer, this is how you remove time components:
public func removeTimeStamp(fromDate: Date) -> Date {
guard let date = Calendar.current.date(from: Calendar.current.dateComponents([.year, .month, .day], from: fromDate)) else {
fatalError("Failed to strip time from Date object")
}
return date
}
Now this should be true:
dateStartDate >= removeTimeStamp(fromDate: dateToday)
As Sweeper explained, dateStartDate is at 00:00 of 28/02/2018,
whereas dateToday is the current point in time, which is
on the same day, but after midnight. Therefore dateStartDate >= dateToday evaluates to false.
To compare the timestamps only to day granularity and ignore the
time components you can use
if Calendar.current.compare(dateStartDate, to: dateToday, toGranularity: .day) != .orderedAscending {
print("Yes")
}
This will print "Yes" if dateStartDate is on the same or a later
day than dateToday.
The compare method returns .orderedAscending, .orderedSame,
or .orderedDescending, depending on wether the first date is on
a previous day, the same day, or a later day, than the second date.
try to set your current date Formatter while comapring date.
Below your sample code update:
var dateStartString = "28/02/2018"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy"
dateFormatter.locale = NSLocale.current
guard let dateStartDate = dateFormatter.date(from: dateStartString) else {
fatalError("ERROR: Date conversion failed due to mismatched format.")
}
var dateToday = Date()
print(dateToday)
let dateTodaystr = dateFormatter.string(from: dateToday)
dateToday = dateFormatter.date(from: dateTodaystr)!
print(dateToday)
if(dateStartDate>=dateToday){
print("Yes")
}
else{
print("Today date is 28/02/2018. Why it print No?")
}
You need to timeZone for your dateFormatter:
dateFormatter.timeZone = TimeZone(secondsFromGMT:0)!