I'm trying to get the first and last day of the month in swift.
So far I have the following:
let dateFormatter = NSDateFormatter()
let date = NSDate()
dateFormatter.dateFormat = "yyyy-MM-dd"
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: date)
let month = components.month
let year = components.year
let startOfMonth = ("\(year)-\(month)-01")
But I'm not sure how to get the last date. Is there a built in method I'm missing? Obviously it has to take into account leap years etc.
Swift 3 and 4 drop-in extensions
This actually gets a lot easier with Swift 3+:
You can do it without guard (you could if you wanted to, but because DateComponents is a non-optional type now, it's no longer necessary).
Using iOS 8's startOfDayForDate (now startOfDay), you don't need to manually set the time to 12pm unless you're doing some really crazy calendar calculations across time zones.
It's worth mentioning that some of the other answers claim you can shortcut this by using Calendar.current.date(byAdding: .month, value: 0, to: Date())!, but where this fails, is that it doesn't actually zero out the day, or account for differences in timezones.
Here you go:
extension Date {
func startOfMonth() -> Date {
return Calendar.current.date(from: Calendar.current.dateComponents([.year, .month], from: Calendar.current.startOfDay(for: self)))!
}
func endOfMonth() -> Date {
return Calendar.current.date(byAdding: DateComponents(month: 1, day: -1), to: self.startOfMonth())!
}
}
print(Date().startOfMonth()) // "2018-02-01 08:00:00 +0000\n"
print(Date().endOfMonth()) // "2018-02-28 08:00:00 +0000\n"
You get the first day of the month simply with
let components = calendar.components([.Year, .Month], fromDate: date)
let startOfMonth = calendar.dateFromComponents(components)!
print(dateFormatter.stringFromDate(startOfMonth)) // 2015-11-01
To get the last day of the month, add one month and subtract one day:
let comps2 = NSDateComponents()
comps2.month = 1
comps2.day = -1
let endOfMonth = calendar.dateByAddingComponents(comps2, toDate: startOfMonth, options: [])!
print(dateFormatter.stringFromDate(endOfMonth)) // 2015-11-30
Alternatively, use the rangeOfUnit method which gives you
the start and the length of the month:
var startOfMonth : NSDate?
var lengthOfMonth : NSTimeInterval = 0
calendar.rangeOfUnit(.Month, startDate: &startOfMonth, interval: &lengthOfMonth, forDate: date)
For a date on the last day of month, add the length of the month minus one second:
let endOfMonth = startOfMonth!.dateByAddingTimeInterval(lengthOfMonth - 1)
Updated for Swift5:
extension Date {
var startOfDay: Date {
return Calendar.current.startOfDay(for: self)
}
var startOfMonth: Date {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.year, .month], from: self)
return calendar.date(from: components)!
}
var endOfDay: Date {
var components = DateComponents()
components.day = 1
components.second = -1
return Calendar.current.date(byAdding: components, to: startOfDay)!
}
var endOfMonth: Date {
var components = DateComponents()
components.month = 1
components.second = -1
return Calendar(identifier: .gregorian).date(byAdding: components, to: startOfMonth)!
}
func isMonday() -> Bool {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.weekday], from: self)
return components.weekday == 2
}
}
With Swift 3 & iOS 10 the easiest way I found to do this is Calendar's dateInterval(of:for:):
guard let interval = calendar.dateInterval(of: .month, for: Date()) else { return }
You can then use interval.start and interval.end to get the dates you need.
Swift 3
Many date example for :
Last 6 month,
last 3 month,
yesterday, last 7 day, last 30 day, previous month,
current month start & end, last month start & end date
let startDate = dateFormatter.string(from: Date().getThisMonthStart()!)
let endDate = dateFormatter.string(from: Date().getThisMonthEnd()!)
extension Date {
func getLast6Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -6, to: self)
}
func getLast3Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -3, to: self)
}
func getYesterday() -> Date? {
return Calendar.current.date(byAdding: .day, value: -1, to: self)
}
func getLast7Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -7, to: self)
}
func getLast30Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -30, to: self)
}
func getPreviousMonth() -> Date? {
return Calendar.current.date(byAdding: .month, value: -1, to: self)
}
// This Month Start
func getThisMonthStart() -> Date? {
let components = Calendar.current.dateComponents([.year, .month], from: self)
return Calendar.current.date(from: components)!
}
func getThisMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month += 1
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month Start
func getLastMonthStart() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month End
func getLastMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
}
Swift 4
If you only need the ordinal day:
func lastDay(ofMonth m: Int, year y: Int) -> Int {
let cal = Calendar.current
var comps = DateComponents(calendar: cal, year: y, month: m)
comps.setValue(m + 1, for: .month)
comps.setValue(0, for: .day)
let date = cal.date(from: comps)!
return cal.component(.day, from: date)
}
lastDay(ofMonth: 2, year: 2018) // 28
lastDay(ofMonth: 2, year: 2020) // 29
This is the simplest way that I found (Swift 5+):
extension Date {
func getStart(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.start
}
func getEnd(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.end
}
}
Here is easiest solution:
extension Date {
func startOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return (interval?.start.toLocalTime())! // Without toLocalTime it give last months last date
}
func endOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return interval!.end
}
// Convert UTC (or GMT) to local time
func toLocalTime() -> Date {
let timezone = TimeZone.current
let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
return Date(timeInterval: seconds, since: self)
}}
and then call these with your date instance:
print(Date().startOfMonth())
print(Date().endOfMonth())
2017...
First, get the month you need:
let cal = Calendar.current
let d = Calendar.current.date(byAdding: .month, value: 0, to: Date())!
// for "last month" just use -1, for "next month" just use 1, etc
To get the day-of-the-week for the first day of the month:
let c = cal.dateComponents([.year, .month], from: d)
let FDOM = cal.date(from: c)!
let dowFDOM = cal.component(.weekday, from: FDOM)
print("the day-of-week on the 1st is ... \(dowFDOM)")
// so, that's 1=Sunday, 2=Monday, etc.
To get the number of days in the month:
let r = cal.range(of: .day, in: .month, for: d)!
let kDays = r.count
print("the number of days is ... \(kDays)")
With Swift 3, you can choose one of the two following patters in order to retrieve the first and last days of a month.
#1. Using Calendar dateComponents(_:from:), date(from:) and date(byAdding:to:wrappingComponents:) methods
With this pattern, you first get the date of the first day of a month then add a month and remove a day from it in order to get the date of the last day of the month. The Playground code below shows how to set it:
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get first day of month
let firstDayComponents = calendar.dateComponents([.year, .month], from: date)
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
let lastDayComponents = DateComponents(month: 1, day: -1)
let lastDay = calendar.date(byAdding: lastDayComponents, to: firstDay)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // Prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // Prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // Prints: 31 March 2017 at 00:00:00 CEST
#2. Using Calendar range(of:in:for:), dateComponents(_:from:) and date(from:) and methods
With this pattern, you get a range of absolute day values in a month and then retrieve the dates of the first day and last day of the month from it. The Playground code below shows how to set it:
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get range of days in month
let range = calendar.range(of: .day, in: .month, for: date)! // Range(1..<32)
// Get first day of month
var firstDayComponents = calendar.dateComponents([.year, .month], from: date)
firstDayComponents.day = range.lowerBound
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
var lastDayComponents = calendar.dateComponents([.year, .month], from: date)
lastDayComponents.day = range.upperBound - 1
//lastDayComponents.day = range.count // also works
let lastDay = calendar.date(from: lastDayComponents)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // prints: 31 March 2017 at 00:00:00 CEST
In swift 3, if you put 0 to day component you can get the last day of the month. There's an example code:
public func isMoreDays(date: Date, asc: Bool)->Bool{
//components
var dayComponents = self.getDateComponents(date: date)
//asc is true if ascendant or false if descendant
dayComponents.day = asc ? 0 : 1
//plus 1 to month 'cos if you set up day to 0 you are going to the previous month
dayComponents.month = asc ? dayComponents.month! + 1 : dayComponents.month
//instantiate calendar and get the date
let calendar : Calendar = NSCalendar.current
let day = calendar.date(from: dayComponents)
//date comparison
if(day?.compare(date) == .orderedSame){
return false
}
return true
}
You can use the following extensions here :
let today = Date()
let startOfMonth = today.beginning(of: .month)
let endOfMonth = today.end(of: .month)
I'm wondering if there is some new and awesome possibility to get the amount of days between two NSDates in Swift / the "new" Cocoa?
E.g. like in Ruby I would do:
(end_date - start_date).to_i
You have to consider the time difference as well. For example if you compare the dates 2015-01-01 10:00 and 2015-01-02 09:00, days between those dates will return as 0 (zero) since the difference between those dates is less than 24 hours (it's 23 hours).
If your purpose is to get the exact day number between two dates, you can work around this issue like this:
// Assuming that firstDate and secondDate are defined
// ...
let calendar = NSCalendar.currentCalendar()
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDayForDate(firstDate)
let date2 = calendar.startOfDayForDate(secondDate)
let flags = NSCalendarUnit.Day
let components = calendar.components(flags, fromDate: date1, toDate: date2, options: [])
components.day // This will return the number of day(s) between dates
Swift 3 and Swift 4 Version
let calendar = Calendar.current
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: firstDate)
let date2 = calendar.startOfDay(for: secondDate)
let components = calendar.dateComponents([.day], from: date1, to: date2)
Here is my answer for Swift 2:
func daysBetweenDates(startDate: NSDate, endDate: NSDate) -> Int
{
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Day], fromDate: startDate, toDate: endDate, options: [])
return components.day
}
I see a couple Swift3 answers so I'll add my own:
public static func daysBetween(start: Date, end: Date) -> Int {
Calendar.current.dateComponents([.day], from: start, to: end).day!
}
The naming feels more Swifty, it's one line, and using the latest dateComponents() method.
Here is very nice, Date extension to get difference between dates in years, months, days, hours, minutes, seconds
extension Date {
func years(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.year], from: sinceDate, to: self).year
}
func months(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.month], from: sinceDate, to: self).month
}
func days(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.day], from: sinceDate, to: self).day
}
func hours(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.hour], from: sinceDate, to: self).hour
}
func minutes(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.minute], from: sinceDate, to: self).minute
}
func seconds(sinceDate: Date) -> Int? {
return Calendar.current.dateComponents([.second], from: sinceDate, to: self).second
}
}
I translated my Objective-C answer
let start = "2010-09-01"
let end = "2010-09-05"
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let startDate:NSDate = dateFormatter.dateFromString(start)
let endDate:NSDate = dateFormatter.dateFromString(end)
let cal = NSCalendar.currentCalendar()
let unit:NSCalendarUnit = .Day
let components = cal.components(unit, fromDate: startDate, toDate: endDate, options: nil)
println(components)
result
<NSDateComponents: 0x10280a8a0>
Day: 4
The hardest part was that the autocompletion insists fromDate and toDate would be NSDate?, but indeed they must be NSDate! as shown in the reference.
I don't see how a good solution with an operator would look like, as you want to specify the unit differently in each case. You could return the time interval, but than won't you gain much.
Update for Swift 3 iOS 10 Beta 4
func daysBetweenDates(startDate: Date, endDate: Date) -> Int {
let calendar = Calendar.current
let components = calendar.dateComponents([Calendar.Component.day], from: startDate, to: endDate)
return components.day!
}
Swift 5. Thanks to Emin Buğra Saral above for the startOfDay suggestion.
extension Date {
func daysBetween(date: Date) -> Int {
return Date.daysBetween(start: self, end: date)
}
static func daysBetween(start: Date, end: Date) -> Int {
let calendar = Calendar.current
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: start)
let date2 = calendar.startOfDay(for: end)
let a = calendar.dateComponents([.day], from: date1, to: date2)
return a.value(for: .day)!
}
}
Usage:
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let start = dateFormatter.date(from: "2017-01-01")!
let end = dateFormatter.date(from: "2018-01-01")!
let diff = Date.daysBetween(start: start, end: end) // 365
// or
let diff = start.daysBetween(date: end) // 365
Here is the answer for Swift 3 (tested for IOS 10 Beta)
func daysBetweenDates(startDate: Date, endDate: Date) -> Int
{
let calendar = Calendar.current
let components = calendar.components([.day], from: startDate, to: endDate, options: [])
return components.day!
}
Then you can call it like this
let pickedDate: Date = sender.date
let NumOfDays: Int = daysBetweenDates(startDate: pickedDate, endDate: Date())
print("Num of Days: \(NumOfDays)")
Swift 5
Working, you need to set the time to be the same for both days, if you are off by seconds it will be wrong
func daysBetween(start: Date, end: Date) -> Int {
let start = Calendar.current.date(bySettingHour: 0, minute: 0, second: 0, of: start)!
let end = Calendar.current.date(bySettingHour: 0, minute: 0, second: 0, of: end)!
return Calendar.current.dateComponents([.day], from: start, to: end).day ?? 0
}
The things built into swift are still very basic. As they should be at this early stage. But you can add your own stuff with the risk that comes with overloading operators and global domain functions. They will be local to your module though.
let now = NSDate()
let seventies = NSDate(timeIntervalSince1970: 0)
// Standard solution still works
let days = NSCalendar.currentCalendar().components(.CalendarUnitDay,
fromDate: seventies, toDate: now, options: nil).day
// Flashy swift... maybe...
func -(lhs:NSDate, rhs:NSDate) -> DateRange {
return DateRange(startDate: rhs, endDate: lhs)
}
class DateRange {
let startDate:NSDate
let endDate:NSDate
var calendar = NSCalendar.currentCalendar()
var days: Int {
return calendar.components(.CalendarUnitDay,
fromDate: startDate, toDate: endDate, options: nil).day
}
var months: Int {
return calendar.components(.CalendarUnitMonth,
fromDate: startDate, toDate: endDate, options: nil).month
}
init(startDate:NSDate, endDate:NSDate) {
self.startDate = startDate
self.endDate = endDate
}
}
// Now you can do this...
(now - seventies).months
(now - seventies).days
This is an updated version of Emin's answer for Swift 5 that incorporates the suggestion to use noon instead of midnight as the definitive time for comparing days. It also handles the potential failure of various date functions by returning an optional.
///
/// This is an approximation; it does not account for time differences. It will set the time to 1200 (noon) and provide the absolute number
/// of days between now and the given date. If the result is negative, it should be read as "days ago" instead of "days from today."
/// Returns nil if something goes wrong initializing or adjusting dates.
///
func daysFromToday() -> Int?
{
let calendar = NSCalendar.current
// Replace the hour (time) of both dates with noon. (Noon is less likely to be affected by DST changes, timezones, etc. than midnight.)
guard let date1 = calendar.date(bySettingHour: 12, minute: 00, second: 00, of: calendar.startOfDay(for: Date())),
let date2 = calendar.date(bySettingHour: 12, minute: 00, second: 00, of: calendar.startOfDay(for: self)) else
{
return nil
}
return calendar.dateComponents([.day], from: date1, to: date2).day
}
Here is my answer for Swift 3:
func daysBetweenDates(startDate: NSDate, endDate: NSDate, inTimeZone timeZone: TimeZone? = nil) -> Int {
var calendar = Calendar.current
if let timeZone = timeZone {
calendar.timeZone = timeZone
}
let dateComponents = calendar.dateComponents([.day], from: startDate.startOfDay, to: endDate.startOfDay)
return dateComponents.day!
}
You could use the following extension:
public extension Date {
func daysTo(_ date: Date) -> Int? {
let calendar = Calendar.current
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: self)
let date2 = calendar.startOfDay(for: date)
let components = calendar.dateComponents([.day], from: date1, to: date2)
return components.day // This will return the number of day(s) between dates
}
}
Then, you can call it like this:
startDate.daysTo(endDate)
There's hardly any Swift-specific standard library yet; just the lean basic numeric, string, and collection types.
It's perfectly possible to define such shorthands using extensions, but as far as the actual out-of-the-box APIs goes, there is no "new" Cocoa; Swift just maps directly to the same old verbose Cocoa APIs as they already exist.
I'm going to add my version even though this thread is a year old. My code looks like this:
var name = txtName.stringValue // Get the users name
// Get the date components from the window controls
var dateComponents = NSDateComponents()
dateComponents.day = txtDOBDay.integerValue
dateComponents.month = txtDOBMonth.integerValue
dateComponents.year = txtDOBYear.integerValue
// Make a Gregorian calendar
let calendar = NSCalendar(identifier: NSCalendarIdentifierGregorian)
// Get the two dates we need
var birthdate = calendar?.dateFromComponents(dateComponents)
let currentDate = NSDate()
var durationDateComponents = calendar?.components(NSCalendarUnit.CalendarUnitDay, fromDate: birthdate!, toDate: currentDate, options: nil)
let numberOfDaysAlive = durationDateComponents?.day
println("\(numberOfDaysAlive!)")
txtGreeting.stringValue = "Hello \(name), You have been alive for \(numberOfDaysAlive!) days."
I hope it helps someone.
Cheers,
Erin's method updated to Swift 3, This shows days from today (disregarding time of day)
func daysBetweenDates( endDate: Date) -> Int
let calendar: Calendar = Calendar.current
let date1 = calendar.startOfDay(for: Date())
let date2 = calendar.startOfDay(for: secondDate)
return calendar.dateComponents([.day], from: date1, to: date2).day!
}
This returns an absolute difference in days between some Date and today:
extension Date {
func daysFromToday() -> Int {
return abs(Calendar.current.dateComponents([.day], from: self, to: Date()).day!)
}
}
and then use it:
if someDate.daysFromToday() >= 7 {
// at least a week from today
}
easier option would be to create a extension on Date
public extension Date {
public var currentCalendar: Calendar {
return Calendar.autoupdatingCurrent
}
public func daysBetween(_ date: Date) -> Int {
let components = currentCalendar.dateComponents([.day], from: self, to: date)
return components.day!
}
}
Swift 3.2
extension DateComponentsFormatter {
func difference(from fromDate: Date, to toDate: Date) -> String? {
self.allowedUnits = [.year,.month,.weekOfMonth,.day]
self.maximumUnitCount = 1
self.unitsStyle = .full
return self.string(from: fromDate, to: toDate)
}
}
All answer is good. But for Localizations we need calculates a number of decimal days in between two dates. so we can provide the sustainable decimal format.
// This method returns the fractional number of days between to dates
func getFractionalDaysBetweenDates(date1: Date, date2: Date) -> Double {
let components = Calendar.current.dateComponents([.day, .hour], from: date1, to: date2)
var decimalDays = Double(components.day!)
decimalDays += Double(components.hour!) / 24.0
return decimalDays
}
Nice handy one liner :
extension Date {
var daysFromNow: Int {
return Calendar.current.dateComponents([.day], from: Date(), to: self).day!
}
}
Swift 3 - Days from today until date
func daysUntilDate(endDateComponents: DateComponents) -> Int
{
let cal = Calendar.current
var components = cal.dateComponents([.era, .year, .month, .day], from: NSDate() as Date)
let today = cal.date(from: components)
let otherDate = cal.date(from: endDateComponents)
components = cal.dateComponents([Calendar.Component.day], from: (today! as Date), to: otherDate!)
return components.day!
}
Call function like this
// Days from today until date
var examnDate = DateComponents()
examnDate.year = 2016
examnDate.month = 12
examnDate.day = 15
let daysCount = daysUntilDate(endDateComponents: examnDate)
extension Date {
func daysFromToday() -> Int {
return Calendar.current.dateComponents([.day], from: self, to: Date()).day!
}
}
Then use it like
func dayCount(dateString: String) -> String{
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "MMM dd,yyyy hh:mm a"
let fetchedDate = dateFormatter.date(from: dateString)
let day = fetchedDate?.daysFromToday()
if day! > -1{
return "\(day!) days passed."
}else{
return "\(day! * -1) days left."
}
}
extension Date {
static func - (recent: Date, previous: Date) -> DateComponents {
var dateComponents = DateComponents()
dateComponents.year = Calendar.current.dateComponents([.day], from: previous, to: recent).year
dateComponents.month = Calendar.current.dateComponents([.month], from: previous, to: recent).month
dateComponents.day = Calendar.current.dateComponents([.day], from: previous, to: recent).day
dateComponents.hour = Calendar.current.dateComponents([.hour], from: previous, to: recent).hour
dateComponents.minute = Calendar.current.dateComponents([.minute], from: previous, to: recent).minute
dateComponents.second = Calendar.current.dateComponents([.second], from: previous, to: recent).second
return dateComponents
}
}
func completeOffset(from date:Date) -> String? {
let formatter = DateComponentsFormatter()
formatter.unitsStyle = .brief
return formatter.string(from: Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date, to: self))
}
if you need year month days and hours as string use this
var tomorrow = Calendar.current.date(byAdding: .day, value: 1, to: Date())!
let dc = tomorrow.completeOffset(from: Date())
2017 version, copy and paste
func simpleIndex(ofDate: Date) -> Int {
// index here just means today 0, yesterday -1, tomorrow 1 etc.
let c = Calendar.current
let todayRightNow = Date()
let d = c.date(bySetting: .hour, value: 13, of: ofDate)
let t = c.date(bySetting: .hour, value: 13, of: todayRightNow)
if d == nil || today == nil {
print("weird problem simpleIndex#ofDate")
return 0
}
let r = c.dateComponents([.day], from: today!, to: d!)
// yesterday is negative one, tomorrow is one
if let o = r.value(for: .day) {
return o
}
else {
print("another weird problem simpleIndex#ofDate")
return 0
}
}
let calendar = NSCalendar.currentCalendar();
let component1 = calendar.component(.Day, fromDate: fromDate)
let component2 = calendar.component(.Day, fromDate: toDate)
let difference = component1 - component2
Swift 5.2.4 solution:
import UIKit
let calendar = Calendar.current
let start = "2010-09-01"
let end = "2010-09-05"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let firstDate = dateFormatter.date(from: start)!
let secondDate = dateFormatter.date(from: end)!
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: firstDate)
let date2 = calendar.startOfDay(for: secondDate)
let components = calendar.dateComponents([Calendar.Component.day], from: date1, to: date2)
components.day // This will return the number of day(s) between dates
iOS Date() returns date with at least microsecond precision.
I checked this statement by calling Date().timeIntervalSince1970 which results in 1490891661.074981
Then I need to convert date into string with microsecond precision.
I am using DateFormatter in following way:
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSZZZZZ"
print(formatter.string(from: date))
which results in
"2017-03-30T16:34:21.075000Z"
Now if we compare two results:
1490891661.074981 and "2017-03-30T16:34:21.075000Z"
we can notice that DateFormatter rounds date to millisecond precision while still presenting zeros for microseconds.
Does anybody know how to configure DateFormatter so I can keep microseconds and get correct result: "2017-03-30T16:34:21.074981Z"?
Thanks to #MartinR for solving first half of my problem and to #ForestKunecke for giving me tips how to solve second half of the problem.
Based on their help I created ready to use solution which converts date from string and vice versa with microsecond precision:
public final class MicrosecondPrecisionDateFormatter: DateFormatter {
private let microsecondsPrefix = "."
override public init() {
super.init()
locale = Locale(identifier: "en_US_POSIX")
timeZone = TimeZone(secondsFromGMT: 0)
}
required public init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override public func string(from date: Date) -> String {
dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
let components = calendar.dateComponents(Set([Calendar.Component.nanosecond]), from: date)
let nanosecondsInMicrosecond = Double(1000)
let microseconds = lrint(Double(components.nanosecond!) / nanosecondsInMicrosecond)
// Subtract nanoseconds from date to ensure string(from: Date) doesn't attempt faulty rounding.
let updatedDate = calendar.date(byAdding: .nanosecond, value: -(components.nanosecond!), to: date)!
let dateTimeString = super.string(from: updatedDate)
let string = String(format: "%#.%06ldZ",
dateTimeString,
microseconds)
return string
}
override public func date(from string: String) -> Date? {
dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
guard let microsecondsPrefixRange = string.range(of: microsecondsPrefix) else { return nil }
let microsecondsWithTimeZoneString = String(string.suffix(from: microsecondsPrefixRange.upperBound))
let nonDigitsCharacterSet = CharacterSet.decimalDigits.inverted
guard let timeZoneRangePrefixRange = microsecondsWithTimeZoneString.rangeOfCharacter(from: nonDigitsCharacterSet) else { return nil }
let microsecondsString = String(microsecondsWithTimeZoneString.prefix(upTo: timeZoneRangePrefixRange.lowerBound))
guard let microsecondsCount = Double(microsecondsString) else { return nil }
let dateStringExludingMicroseconds = string
.replacingOccurrences(of: microsecondsString, with: "")
.replacingOccurrences(of: microsecondsPrefix, with: "")
guard let date = super.date(from: dateStringExludingMicroseconds) else { return nil }
let microsecondsInSecond = Double(1000000)
let dateWithMicroseconds = date + microsecondsCount / microsecondsInSecond
return dateWithMicroseconds
}
}
Usage:
let formatter = MicrosecondPrecisionDateFormatter()
let date = Date(timeIntervalSince1970: 1490891661.074981)
let formattedString = formatter.string(from: date) // 2017-03-30T16:34:21.074981Z
The resolution of (NS)DateFormatter is limited to milliseconds, compare
NSDateFormatter milliseconds bug. A possible solution is to retrieve all date components (up to
nanoseconds) as numbers and do a custom string formatting. The date formatter can still be used for the timezone string.
Example:
let date = Date(timeIntervalSince1970: 1490891661.074981)
let formatter = DateFormatter()
formatter.dateFormat = "ZZZZZ"
let tzString = formatter.string(from: date)
let cal = Calendar.current
let comps = cal.dateComponents([.year, .month, .day, .hour, .minute, .second, .nanosecond],
from: date)
let microSeconds = lrint(Double(comps.nanosecond!)/1000) // Divide by 1000 and round
let formatted = String(format: "%04ld-%02ld-%02ldT%02ld:%02ld:%02ld.%06ld",
comps.year!, comps.month!, comps.day!,
comps.hour!, comps.minute!, comps.second!,
microSeconds) + tzString
print(formatted) // 2017-03-30T18:34:21.074981+02:00
Solution by #Vlad Papko has some issue:
For dates like following:
2019-02-01T00:01:54.3684Z
it can make string with extra zero:
2019-02-01T00:01:54.03684Z
Here is fixed solution, it's ugly, but works without issues:
override public func string(from date: Date) -> String {
dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
let components = calendar.dateComponents(Set([Calendar.Component.nanosecond]), from: date)
let nanosecondsInMicrosecond = Double(1000)
let microseconds = lrint(Double(components.nanosecond!) / nanosecondsInMicrosecond)
// Subtract nanoseconds from date to ensure string(from: Date) doesn't attempt faulty rounding.
let updatedDate = calendar.date(byAdding: .nanosecond, value: -(components.nanosecond!), to: date)!
let dateTimeString = super.string(from: updatedDate)
let stingWithMicroseconds = "\(date.timeIntervalSinceReferenceDate)"
let dotIndex = stingWithMicroseconds.lastIndex(of: ".")!
let hasZero = stingWithMicroseconds[stingWithMicroseconds.index(after: dotIndex)] == "0"
let format = hasZero ? "%#.%06ldZ" : "%#.%6ldZ"
let string = String(format: format,
dateTimeString,
microseconds)
return string
}
It is a bit of a hack, but not that complex and 100% Swift:
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss.'MICROS'xx"
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
// Get the number of microseconds with a precision of 6 digits
let now = Date()
let dateParts = Calendar.current.dateComponents([.nanosecond], from: now)
let microSeconds = Int((Double(dateParts.nanosecond!) / 1000).rounded(.toNearestOrEven))
let microSecPart = String(microSeconds).padding(toLength: 6, withPad: "0", startingAt: 0)
// Format the date and add in the microseconds
var timestamp = dateFormatter.string(from: now)
timestamp = timestamp.replacingOccurrences(of: "MICROS", with: microSecPart)