I'm grabbing data from an api, and one of the values I'm getting is for day of the week, the data returned from api looks like this:
"time": 1550376000
I created this function to get the date:
func getDate(value: Int) -> String {
let date = Calendar.current.date(byAdding: .day, value: value, to: Date())
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "E"
return dateFormatter.string(from: date!)
}
but was told there is a much safer way to get it instead of assuming we get consecutive days starting with today. Does anyone know how to build a date out of the time field (it is seconds since midnight 1970) and then use Calendar and DateComponent to figure out the day?
Looks like you are receiving json data so you should structure your data and conform to Decodable protocol to convert your data to an object properly structured.
struct Object: Decodable {
let time: Date
}
Don't forget to set the decoder dateDecodingStrategy property to secondsSince1970
do {
let obj = try decoder.decode(Object.self, from: Data(json.utf8))
let date = obj.time // "Feb 17, 2019 at 1:00 AM"
print(date.description(with: .current))// "Sunday, February 17, 2019 at 1:00:00 AM Brasilia Standard Time\n"
} catch {
print(error)
}
Then you just need to get the weekday component (1...7 = Sun...Sat) and get the calendar shortWeekdaySymbols (localised), subtract 1 from the component value and use it as index to get correspondent symbol. Same approach I used in this post How to print name of the day of the week? to get the full week day name:
extension Date {
var weekDay: Int {
return Calendar.current.component(.weekday, from: self)
}
var weekdaySymbolShort: String {
return Calendar.current.shortWeekdaySymbols[weekDay-1]
}
}
print(date.weekdaySymbolShort) // "Sun\n"
You can use Calendar to get date component from the Date:
let date = Date(timeIntervalSince1970: time)// time is your value 1550376000
let timeComponents = Calendar.current.dateComponents([.weekday, .day, .month, .year], from: date)
print("\(timeComponents.weekday) \(timeComponents.day!) \(timeComponents.month!) \(timeComponents.year!)") // print "7 16 2 2019"
print("\(\(Calendar.current.shortWeekdaySymbols[timeComponents.weekday!-1]))") // print "Sat"
Hope this helps.
Related
I am having a small issue with getting the total days in a month using Swift.
I have extended the Date class and created this function:
func daysInMonth() -> Int {
print(self.day) ##30
print(self.month) ##12
print(self) ## 2021-11-30 23:46:29 +0000
print(Calendar.current.range(of: .day, in: .month, for: self)?.count) ##31
return Calendar.current.range(of: .day, in: .month, for: self)?.count ?? 0
}
I have set the Date&Time to the 30th of November, at 11:45 PM in the settings of my Mac, in Preferences.
I called the above function at 11:46 PM and obtained the above results (inline, next to the print statements).
The date output is correct as well as the day. The month output is wrong and the result is 31 days in the month of November.
If I run this exact same code before 10:00 PM, I get the right result which is 30 days.
Does anyone know why this is happening?
Thank you,
Paprika
It's a GMT offset issue combined with the current day in a month.
When you create a date without set a day, it will be set to the first day of the month.
So, if your timezone offset is for example -4 means your are 4 hours behind the GMT 0 and by default the timezone defined at Calendar.current is equal the system timezone. So what it means? Means you'll obtain the previous month if you test it in a boundary of 23 + (-4) or the next month if your offset is positive.
You can test this behaviour copying'n paste the following code in the Playground.
func getDaysInMonth(month: Int, year: Int, offset: Int = 0) -> Int? {
let someDate = DateComponents(year: year, month: month, hour: 3)
var current = Calendar.current
let timezone = TimeZone(secondsFromGMT: 60 * 60 * offset)!
current.timeZone = timezone
guard let someDay = current.date(from: someDate) else { return nil }
print("date: \(someDay)") // this will always
return someDay.daysInCurrentMonth
}
for hour in -12...12 {
print("hour: \(hour)\ndays: \(getDaysInMonth(month: 10, year: 2021, offset: hour) ?? -1)")
print("---\n")
}
extension Date {
var daysInCurrentMonth: Int? {
Calendar.current.range(of: .day, in: .month, for: self)?.count
}
}
Notice the days will change starting by your current system time zone (notice only the month will change).
How to fix this?
In your case, I guess you just want to show how many days a month have, so you can just set the to zero like this:
TimeZone(secondsFromGMT: 0)
Do this change at a instance of Calendar.current and check if it works for you.
It appears there something wrong with your Date extension methods for .day and .month.
Without seeing code it's hard to determine what the problem is though. Below is some code for returning the current month (Int) and current numbered day of month (Int)
extension Date
{
var month: Int
{
let date = Date()
let calendar = Calendar.current
let components = calendar.dateComponents([.month], from: date)
return components.month
}
var day: Int
{
let date = Date()
let calendar = Calendar.current
let components = calendar.dateComponents([.day], from: self)
return components.day
}
}
Please also ensure your time/date settings are correct on your mac/simulator/device. If these are wrong - it could have been jumping to a different month if you were in a timezone that was ahead a few hours.
How to get the current date in unix-epoch?
timeIntervalSince1970 prints the current time. Is there any way to get today's time at 12 AM?
For example, The current time is : Jan 7, 2018 5:30 PM. timeIntervalSince1970 will print the current time i.e. 1546903800000.
Current date in epoch system will be Jan 7, 2018 00:00 AM. i.e 1546848000000
This can be done very simply using the following code. No need for date components or other complications.
var calendar = Calendar.current
// Use the following line if you want midnight UTC instead of local time
//calendar.timeZone = TimeZone(secondsFromGMT: 0)
let today = Date()
let midnight = calendar.startOfDay(for: today)
let tomorrow = calendar.date(byAdding: .day, value: 1, to: midnight)!
let midnightEpoch = midnight.timeIntervalSince1970
let tomorrowEpoch = tomorrow.timeIntervalSince1970
I would do this with components.
Assuming you need time in seconds as defined by time(2). If you need in milliseconds as defined by time(3), then you can multiply it out by 1000.
// Get right now as it's `DateComponents`.
let now = Calendar.current.dateComponents(in: .current, from: Date())
// Create the start of the day in `DateComponents` by leaving off the time.
let today = DateComponents(year: now.year, month: now.month, day: now.day)
let dateToday = Calendar.current.date(from: today)!
print(dateToday.timeIntervalSince1970)
// Add 1 to the day to get tomorrow.
// Don't worry about month and year wraps, the API handles that.
let tomorrow = DateComponents(year: now.year, month: now.month, day: now.day! + 1)
let dateTomorrow = Calendar.current.date(from: tomorrow)!
print(dateTomorrow.timeIntervalSince1970)
You can get yesterday by subtracting 1.
If you need this in the universal time (UTC, GMT, Z… whatever name you give universal time), then use the following.
let utc = TimeZone(abbreviation: "UTC")!
let now = Calendar.current.dateComponents(in: utc, from: Date())
Use this extension to get today's and tomorrow's date
extension Date {
static var tomorrow: Date { return Date().dayAfter }
static var today: Date {return Date()}
var dayAfter: Date {
return Calendar.current.date(byAdding: .day, value: 1, to: Date())!
}
}
Also try adding following code in date extension:
extension Date
{
var startOfDay: Date
{
return Calendar.current.startOfDay(for: self)
}
func getDate(dayDifference: Int) -> Date {
var components = DateComponents()
components.day = dayDifference
return Calendar.current.date(byAdding: components, to:startOfDay)!
}
}
You can use the following method to get any date by adding days or months or years
by specifying the Calendar Component and the increment value of this component:
func getSpecificDate(byAdding component: Calendar.Component, value: Int) -> Date {
let noon = Calendar.current.date(bySettingHour: 12, minute: 0, second: 0, of: self)!
return Calendar.current.date(byAdding: component, value: value, to: noon)!
}
Where the component wil be one from the following option :
( .day , .month , .year ) and the value will be the amount you want to add for this component
for example to get the next year date you can use the following code:
var nextYear = getSpecificDate(byAdding: .year, value: 1).timeIntervalSince1970
For some strange reason when executing a HKActivitySummaryQuery the returned date component for each summary is a day behind.
The query returns data from the correct date but the dateComponents date of the data is behind by a day. I've tried setting the timezone and locale but results remain the same.
Summary Model
struct ActivitySummary {
init?(_ summary: HKActivitySummary) {
var calendar = Calendar.current
calendar.timeZone = TimeZone.current
guard let date = summary.dateComponents(for: calendar).date else { return nil }
print("ORIGINAL: ", date.description(with: Locale.current))
//Expected: Tuesday, January 30, 2018 at 7:00:00 PM Eastern Standard Time
//Results: Monday, January 29, 2018 at 7:00:00 PM Eastern Standard Time
let other = calendar.dateComponents( [ .year, .month, .day ], from: date)
print("START OF DAY: ", date.startOfDay.description(with: Locale.current))
//Expected: Tuesday, January 30, 2018 at 12:00:00 AM Eastern Standard Time
//Results: Monday, January 29, 2018 at 12:00:00 AM Eastern Standard Time
}
}
HKAcitivitySummaryQuery
func summaryQuery(){
let predicate = HKQuery.predicate(forActivitySummariesBetweenStart: fromDate.components(), end: toDate!.components())
let query = HKActivitySummaryQuery(predicate: predicate) { (query, summaries, error) in
guard let summaries = summaries, summaries.count > 0 else {
return
}
//
var activitySummaries: [ActivitySummary] = []
activitySummaries = summaries.compactMap({
ActivitySummary($0)
})
}
}
Maybe the calendar you're working with is wrong. set your calendar like this :
let calendar = Calendar.current
Try manually setting the time zone for the DateComponents before converting them into a Date:
let calendar = Calendar.current
var dateComponents = summary.dateComponents(in: calendar)
dateComponents.timeZone = calendar.timeZone
let date = dateComponents.date!
The DateComponents associated with each HKActivitySummary do not include a time zone. The resulting Date may be slightly off from what you’re expecting because it’s not in the correct time zone (Swift defaults to UTC if a time zone is not specified). Manually specifying the time zone should resolve this issue.
I know how to get local date and time, but what I want to do is getting the date and time from different places. For example, I want to find out what the time and date is in New York. How can i solve this simple problem?
Here is my code for local date and time :
let date = NSDate()
let calendar = Calendar.current
let components = calendar.dateComponents([.hour, .minute, .month, .year, .day, .second, .weekOfMonth], from: date as Date)
let currentDate = calendar.date(from: components)
I searched about it here, but i didn't find what i want and I'm still looking for the date libaries. If you know any source or sample to redirect me, I really appreciate that.
There are several different concepts involved here, and we need to understand (almost) all of them to get this right...
1) a Date (NSDate as was, in Swift) is an absolute point in time - it's slightly mis-named, because it has nothing to do with an actual date like 13th November 2017, because to get to that we need to define ...
2) a Calendar, because 13th November 2017 in the western Gregorian calendar could also be 23rd Safar 1439 in the Islamic calendar, or the 24th of Heshvan 5778 in the Hebrew calendar, or some other things in the many other calendars that iOS & MacOS support;
3) in turn Calendar changes not only what values are returned in the DateComponents that we have to use to unpack a Date + Calendar into days, months, years & eras (e.g. BC/AD), or even week number, etc..., but also some calendars might not have the same components as others;
4) time-of-day (as you know) depends on TimeZone, so the same absolute time can be one of many different times "o'clock" depending on where you are. It may also (as you can see in the example below) change the date as well as the "o'clock". This of course could be automatic (where you are) or set by the programmer;
5) further, we have DateFormatter (which is a convenience that wraps up DateComponents), because 13th November 2017 could be represented as 13/11/17 or 11/13/17 depending on whether you are British or American. We may also wish to choose whether we use text or numeric months, and, if displaying times, whether we want 12 hour or 24 hour format - all of these are covered by DateFormatter, but text representation may be "13e Novembre 2017" if you are French, which introduces the notion of
6) Locale, which can be set, like TimeZone, as being default (as chosen when you set up the device) or specified by the programmer.
The code you posted won't work, because all it does is takes a Date, transforms it through a Calendar to DateComponents (all good so far), but then recreates a Date from the components - all you will get is the original Date - the same absolute point in time.
What I believe from the question and your answers to questions in the comments is that you want a function that takes an absolute time (eg "now") aka a Date and displays it in a specific TimeZone. This works:
func timeComponents(date: Date, timeZone: TimeZone) -> DateComponents {
var calendar = Calendar.current
calendar.timeZone = timeZone
return calendar.dateComponents([.hour, .minute, .month, .year, .day, .second, .weekOfMonth], from: date)
}
let absTime: Date = Date() // Now
let edinburgh = TimeZone(abbreviation: "GMT")!
let newYork = TimeZone(abbreviation: "EST")!
let ec = timeComponents(date: absTime, timeZone: edinburgh)
let nycc = timeComponents(date: absTime, timeZone: newYork)
print(ec)// year: 2017 month: 11 day: 14 hour: 0 minute: 44 second: 10 weekOfMonth: 3 isLeapMonth: false
print(nycc) // year: 2017 month: 11 day: 13 hour: 19 minute: 44 second: 10 weekOfMonth: 3 isLeapMonth: false
... which I think answers the minimum of your question, but to finesse it, we need to move from DateComponents to DateFormatter
func timeString(date: Date, timeZone: TimeZone, timeStyle: DateFormatter.Style) -> String {
let dateFormatter = DateFormatter()
dateFormatter.timeZone = timeZone
dateFormatter.dateStyle = .none
dateFormatter.timeStyle = timeStyle
return dateFormatter.string(from: date)
}
let es = timeString(date: absTime, timeZone: edinburgh, timeStyle: .full)
let nycs = timeString(date: absTime, timeZone: newYork, timeStyle: .full)
print(es) // 12:44:10 AM Greenwich Mean Time
print(nycs) // 7:44:10 PM Eastern Standard Time
You can go on, and start to use Locale, if you want to internationalise your app, but I'l leave that as an exercise!
p.s. These are not all of the concepts - see here
p.p.s. See also this answer and this answer (neither duplicates)
If you just want to format the date to a string, consider using a DateFormatter instead:
let date = Date()
let formatter = DateFormatter()
formatter.timeZone = TimeZone(identifier: "America/New_York")
formatter.dateStyle = .long
formatter.timeStyle = .long
formatter.string(from: date)
If you want to get the date components and process them, use the dateComponents(in:from:) method.
let components = Calendar.current.dateComponents(in: TimeZone(identifier: "America/New_York")!, from: date)
If you don't know the time zone of the place you are searching for, you can use the CoreLocation's CLGeocoder and search on an address string. Then you can get the timezone for that place and translate that into the time you're looking for:
let geocoder = CLGeocoder()
geocoder.geocodeAddressString("New York, New York") { (placemarks, error) in
guard error == nil else {
print("Error")
print(error!.localizedDescription)
return
}
guard let placemarks = placemarks,
let place = placemarks.first else {
print("No results")
return
}
if let timeZone = place.timeZone {
print("TimeZone: \(timeZone.identifier)")
// TimeZone: America/New_York
//Ignore the time zone offset from this one, it will be the difference between the current time and the new york time
let dateInNewYork = Date().addingTimeInterval(TimeInterval.init(timeZone.secondsFromGMT()))
print(dateInNewYork)
// 2017-11-13 15:03:05 +0000
//Or
let formatter = DateFormatter()
formatter.timeZone = TimeZone(identifier: timeZone.identifier)
formatter.dateStyle = .long
formatter.timeStyle = .long
let formattedDateInNewYork = formatter.string(from: Date())
print(formattedDateInNewYork)
// November 13, 2017 at 3:03:05 PM EST
//Or
let components = Calendar.current.dateComponents(in: TimeZone(identifier: timeZone.identifier)!, from: Date())
print(components.date!)
// 2017-11-13 20:03:05 +0000
}
}
I have a date in string format, example:- "2017-07-31" or can be multiple dates (any) in string format. My requirement is to check this date to current date and if it is greater than 0 and less than 15, then that time I have to do another operation.
So first I am converting that date string to in date format. But it is giving one day ago date. Here is my code:
//Date from string
func dateFromString(date : String) -> Date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let currentDate = (dateFormatter.date(from: date))//(from: date))
return currentDate!
}
Ex. my date is "2017-08-30" and this function is returning 2017-08-29 18:30:00 +0000 in date format. It means 1 day ago. I am little bit confuse about dates operation. I read so many blogs also.
After that I have to check this date to current date if it is in between 0 < 15 than I will do other operation.
Comparing two dates:
extension Date {
func daysBetweenDate(toDate: Date) -> Int {
let components = Calendar.current.dateComponents([.day], from: self, to: toDate)
return components.day ?? 0
}
}
If my date is today date and comparing to tomorrow date then also it is giving 0 days difference. Why?
If – for example – the current date is 2017-07-31 at 11AM then the
difference to 2017-08-01 (midnight) is 0 days and 13 hours, and that's
why you get "0 days difference" as result.
What you probably want is to compare the difference between the start
of the current day and the other date in days:
extension Date {
func daysBetween(toDate: Date) -> Int {
let cal = Calendar.current
let startOfToday = cal.startOfDay(for: self)
let startOfOtherDay = cal.startOfDay(for: toDate)
return cal.dateComponents([.day], from: startOfToday, to: startOfOtherDay).day!
}
}
Try this method for convert string to date:
func dateFromString(date : String) -> Date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
dateFormatter.timeZone = TimeZone.init(abbreviation: "UTC")
let currentDate = (dateFormatter.date(from: date))//(from: date))
return currentDate!
}
Try this to compare the time between two dates in seconds :
var seconds = Calendar.current.dateComponents([.second], from: date1!, to: date2!).second ?? 0
seconds = abs(seconds)
let min = seconds/60 // this gives you the number of minutes between two dates
let hours = seconds/3600 // this gives you the number of hours between two dates
let days = seconds/3600*24 // this gives you the number of days between two dates