Swift days between two NSDates

Question

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

Answer 1

The accepted answer won't return the correct day number between two dates. 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)

Answer 2

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
}

Answer 3

I see a couple Swift3 answers so I'll add my own:

public static func daysBetween(start: Date, end: Date) -> Int {
    return Calendar.current.dateComponents([.day], from: start, to: end).day!
}

The naming feels more Swifty, it's one line, and using the latest dateComponents() method.

Answer 4

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.

Answer 5

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
    }

}

Answer 6

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!
}

Answer 7

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)")

Answer 8

Swift 3. 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

Answer 9

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

Answer 10

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!
}

Answer 11

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.

Answer 12

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,

Answer 13

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! 
}

Answer 14

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
}

Answer 15

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."
        }
    }

Answer 16

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)
    }
}

Answer 17

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
}

Answer 18

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)

Answer 19

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!
        }
    }

Answer 20

  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())

Answer 21

Nice handy one liner :

extension Date {
  var daysFromNow: Int {
    return Calendar.current.dateComponents([.day], from: Date(), to: self).day!
  }
}

Answer 22

Swift 4

 func getDateHeader(indexPath: Int) -> String {
    let formatter2 = DateFormatter()
    formatter2.dateFormat = "MM-dd-yyyy"
    var dateDeadline : Date?

    dateDeadline = formatter2.date(from: arrCompletedDate[indexPath] as! String)

    let currentTime = dateDeadline?.unixTimestamp
    let calendar = NSCalendar.current

    let date = NSDate(timeIntervalSince1970: Double(currentTime!))
    if calendar.isDateInYesterday(date as Date) { return "Yesterday" }
    else if calendar.isDateInToday(date as Date) { return "Today" }
    else if calendar.isDateInTomorrow(date as Date) { return "Tomorrow" }
    else {
        let startOfNow = calendar.startOfDay(for: NSDate() as Date)
        let startOfTimeStamp = calendar.startOfDay(for: date as Date)
        let components = calendar.dateComponents([.day], from: startOfNow, to: startOfTimeStamp)
        let day = components.day!
        if day < 1 { return "\(abs(day)) days ago" }
        else { return "In \(day) days" }
    }
}

Answer 23

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
    }
}

Answer 24

let calendar = NSCalendar.currentCalendar();
let component1 = calendar.component(.Day, fromDate: fromDate)
let component2 = calendar.component(.Day, fromDate: toDate)
let difference  = component1 - component2