Get day of week using NSDate

Question

I created a method that is supposed to take in a string in  YYYY-MM-DD  form and spit out an int that represents the dates position in relation to the week it is in  regardless if it overlaps between months   So e g sunday 1 monday 2 and so on    Here is my code       func getDayOfWeek today String - gt Int       var formatter NSDateFormatter   NSDateFormatter       formatter dateFormat    YYYY-MM-DD      var todayDate NSDate   formatter dateFromString today       var myCalendar NSCalendar   NSCalendar calendarIdentifier  NSGregorianCalendar      var myComponents   myCalendar components NSCalendarUnit WeekdayOrdinalCalendarUnit  fromDate  todayDate      var weekDay   myComponents weekdayOrdinal     return weekDay     I know that NSCalendarUnit WeekdayOrdinalCalendar is wrong but I have tried I think most logical combinations  And have also messed around with myComponents weekdayOrdinal e g used mycomponents day or  weekday   Here are my options in what to use   static var EraCalendarUnit  NSCalendarUnit   get   static var YearCalendarUnit  NSCalendarUnit   get   static var MonthCalendarUnit  NSCalendarUnit   get   static var DayCalendarUnit  NSCalendarUnit   get   static var HourCalendarUnit  NSCalendarUnit   get   static var MinuteCalendarUnit  NSCalendarUnit   get   static var SecondCalendarUnit  NSCalendarUnit   get   static var WeekCalendarUnit  NSCalendarUnit   get   static var WeekdayCalendarUnit  NSCalendarUnit   get   static var WeekdayOrdinalCalendarUnit  NSCalendarUnit   get   static var QuarterCalendarUnit  NSCalendarUnit   get   static var WeekOfMonthCalendarUnit  NSCalendarUnit   get   static var WeekOfYearCalendarUnit  NSCalendarUnit   get   static var YearForWeekOfYearCalendarUnit  NSCalendarUnit   get   static var CalendarCalendarUnit  NSCalendarUnit   get   static var TimeZoneCalendarUnit  NSCalendarUnit   get     It is not clear to me since there is no DayOfWeekUnit option  or something similar

User · Answer

There are already a lot of answers here but I think there's another, perhaps better, way of doing this using the correct Calendar APIs.

I'd suggest getting the day of the week using the weekdaySymbols property of Calendar (docs) in an extension to Date:

extension Date {

    /// Returns the day of the week as a `String`, e.g. "Monday"
    var dayOfWeek: String {
        let calendar = Calendar.autoupdatingCurrent
        return calendar.weekdaySymbols[calendar.component(.weekday, from: self) - 1]
    }
}

This requires initialising a Date first, which I would do using a custom DateFormatter:

extension DateFormatter {

    /// returns a `DateFormatter` with the format "yyyy-MM-dd".
    static var standardDate: DateFormatter {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter
    }
}

This can then be called with:

DateFormatter.standardDate.date(from: "2018-09-18")!.dayOfWeek

Why I prefer this:

dayOfWeek does not have to care about time zones because the user's calendar is used, some of the other solutions here will show the incorrect day because time zones are not considered.
It's very likely that you'll need to use dates in the same format in other places so why not create a reusable DateFormatter and use that instead?
weekdaySymbols is localised for you.
weekDaySymbols can be replaced with other options such as shortWeekdaySymbols for "Mon", "Tues" etc.

Please note: This example DateFormatter also doesn't consider time zones or locales, you'll need to set them for what you need. If the dates are always precise, consider setting the time zone TimeZone(secondsFromGMT: 0).

User · Answer

extension Date    var weekdayName  String       let formatter   DateFormatter    formatter dateFormat    E      return formatter string from  self as Date     var weekdayNameFull  String       let formatter   DateFormatter    formatter dateFormat    EEEE      return formatter string from  self as Date    var monthName  String       let formatter   DateFormatter    formatter dateFormat    MMM      return formatter string from  self as Date    var OnlyYear  String       let formatter   DateFormatter    formatter dateFormat    YYYY      return formatter string from  self as Date    var period  String       let formatter   DateFormatter    formatter dateFormat    a      return formatter string from  self as Date    var timeOnly  String       let formatter   DateFormatter    formatter dateFormat    hh   mm      return formatter string from  self as Date    var timeWithPeriod  String       let formatter   DateFormatter    formatter dateFormat    hh   mm a      return formatter string from  self as Date     var DatewithMonth  String       let formatter   DateFormatter    formatter dateStyle    medium          return formatter string from  self as Date        usage  let weekday   Date   weekdayName

User · Answer

The practical solution      Be aware that results are the integers one through seven    Not zero through six    let trivialDayStringsORDINAL         SUN   MON   TUE   WED   THU   FRI   SAT      note that zero is not used   and then      let dow   Calendar current component  weekday  from  someDate  print  trivialDayStringsORDINAL dow

User · Answer

What you are looking for  if I understand the question correctly  is NSCalendarUnit CalendarUnitWeekday  The corresponding property of NSDateComponents is weekday   Note also that your date format is wrong  the full specification can be found here  http   unicode org reports tr35 tr35-6 html    The function can be simplified slightly  using automatic type inference  also you use variables a lot where constants are sufficient  In addition  the function should return an optional which is nil for an invalid input string   Updated code for Swift 3 and later   func getDayOfWeek   today String  - gt  Int        let formatter    DateFormatter       formatter dateFormat    yyyy-MM-dd      guard let todayDate   formatter date from  today  else   return nil       let myCalendar   Calendar identifier   gregorian      let weekDay   myCalendar component  weekday  from  todayDate      return weekDay     Example   if let weekday   getDayOfWeek  2014-08-27         print weekday    else       print  bad input       Original answer for Swift 2   func getDayOfWeek today String - gt Int         let formatter    NSDateFormatter       formatter dateFormat    yyyy-MM-dd      if let todayDate   formatter dateFromString today            let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian           let myComponents   myCalendar components  Weekday  fromDate  todayDate          let weekDay   myComponents weekday         return weekDay       else           return nil

User · Answer

For Swift4 to get weekday from string     func getDayOfWeek today String - gt Int           let formatter    DateFormatter           formatter dateFormat    yyyy-MM-dd          let todayDate   formatter date from  today           let myCalendar   NSCalendar calendarIdentifier  NSCalendar Identifier gregorian           let myComponents   myCalendar components NSCalendar Unit weekday  from  todayDate          let weekDay   myComponents weekday         return weekDay         let weekday   getDayOfWeek today   2018-10-10   print weekday     4

User · Answer

The simple answer  swift 3    Calendar current component  weekday  from  Date

User · Answer

If you want the full  Sunday    Monday    Tuesday    Wednesday  etc   EDIT  There s actually a built in format that returns localized day names   extension NSDate       func dayOfTheWeek   - gt  String                    let dateFormatter   NSDateFormatter           dateFormatter dateFormat    EEEE          return dateFormatter stringFromDate self            My previous solution  for English only    extension NSDate        func dayOfTheWeek   - gt  String            let weekdays                  Sunday                Monday                Tuesday                Wednesday                Thursday                Friday                Saturday                     let calendar  NSCalendar   NSCalendar currentCalendar           let components  NSDateComponents   calendar components  Weekday  fromDate  self          return weekdays components weekday - 1            You don t need to unwrap calendar and components  they are guaranteed by the foundation framework   Usage   print myDate dayOfTheWeek

User · Answer

Swift 3  amp  4  Retrieving the day of the week s number is dramatically simplified in Swift 3 because DateComponents is no longer optional  Here it is as an extension   extension Date       func dayNumberOfWeek   - gt  Int            return Calendar current dateComponents   weekday   from  self  weekday              returns an integer from 1 - 7  with 1 being Sunday and 7 being Saturday print Date   dayNumberOfWeek        4   If you were looking for the written  localized version of the day of week   extension Date       func dayOfWeek   - gt  String            let dateFormatter   DateFormatter           dateFormatter dateFormat    EEEE          return dateFormatter string from  self  capitalized             or use capitalized with  locale  if you want          print Date   dayOfWeek        Wednesday

User · Answer

I ended up needing a few more strings from the date  including date of the week  e g   5th   and month of the year  e g  Aug   Below are all three functions I have created based upon  Martin R s function and modified to return 3 char strings     Date String Helper Functions func getDayOfWeek today String - gt String        let formatter    NSDateFormatter       formatter dateFormat    yyyy-MM-dd      if let todayDate   formatter dateFromString today            let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian           let myComponents   myCalendar components  Weekday  fromDate  todayDate          let weekDay   myComponents weekday         switch weekDay           case 1              return  Sun          case 2              return  Mon          case 3              return  Tue          case 4              return  Wed          case 5              return  Thu          case 6              return  Fri          case 7              return  Sat          default              print  Error fetching days               return  Day                  else           return nil          func getDateOfMonth today String - gt String        let formatter    NSDateFormatter       formatter dateFormat    yyyy-MM-dd      if let todayDate   formatter dateFromString today            let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian           let myComponents   myCalendar components  Day  fromDate  todayDate          let weekDay   myComponents day         switch weekDay           case 1              return  1st          case 2              return  2nd          case 3              return  3rd          case 4              return  4th          case 5              return  5th          case 6              return  6th          case 7              return  7th          case 8              return  8th          case 9              return  9th          case 10              return  10th          case 11              return  11th          case 12              return  12th          case 13              return  13th          case 14              return  14th          case 15              return  15th          case 16              return  16th          case 17              return  17th          case 18              return  18th          case 19              return  19th          case 20              return  20th          case 21              return  21st          case 22              return  22nd          case 23              return  23rd          case 24              return  24th          case 25              return  25th          case 26              return  26th          case 27              return  27th          case 28              return  28th          case 29              return  29th          case 30              return  30th          case 31              return  31st          default              print  Error fetching Date Of Month               return  Day                  else           return nil          func getMonthOfYear today String - gt String        let formatter    NSDateFormatter       formatter dateFormat    yyyy-MM-dd      if let todayDate   formatter dateFromString today            let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian           let myComponents   myCalendar components  Month  fromDate  todayDate          let month   myComponents month         switch month           case 1              return  Jan          case 2              return  Feb          case 3              return  Mar          case 4              return  Apr          case 5              return  May          case 6              return  Jun          case 7              return  Jul          case 8              return  Aug          case 9              return  Sep          case 10              return  Oct          case 11              return  Nov          case 12              return  Dec          default              print  Error fetching months               return  Month                  else           return nil

User · Answer

This code is to find the whole current week  It is written in Swift 2 0    var i   2 var weekday   String       var weekdate   String       var weekmonth   String         IBAction func buttonaction sender  AnyObject         let currentDate   NSDate       let dateFormatter   NSDateFormatter       dateFormatter dateFormat    MMM-dd-yyyy      let dayOfWeekStrings   dateFormatter stringFromDate currentDate      let weekdays   getDayOfWeek dayOfWeekStrings      let calendar   NSCalendar currentCalendar        while  weekdays - weekdays    i  lt  9                let weekFirstDate   calendar dateByAddingUnit  Day  value   -weekdays i   toDate  NSDate    options               let dayFormatter   NSDateFormatter           dayFormatter dateFormat    EEEE          let dayOfWeekString   dayFormatter stringFromDate weekFirstDate           weekday append dayOfWeekString           let dateFormatter   NSDateFormatter           dateFormatter dateFormat    dd          let dateOfWeekString   dateFormatter stringFromDate weekFirstDate           weekdate append dateOfWeekString           let monthFormatter   NSDateFormatter           monthFormatter dateFormat    MMMM          let monthOfWeekString   monthFormatter stringFromDate weekFirstDate           weekmonth append monthOfWeekString           i              for var j   0  j lt 7   j              let day   weekday j      let date   weekdate j      let month   weekmonth j      var wholeweek   date    -    month         day           print wholeweek            func getDayOfWeek today String - gt Int       let formatter    NSDateFormatter       formatter dateFormat    MMM-dd-yyyy      let todayDate   formatter dateFromString today       let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian       let myComponents   myCalendar components  Weekday  fromDate  todayDate      let daynumber   myComponents weekday     return daynumber     The output will be like this   14March Monday  15March Tuesday  16March Wednesday  17March Thursday  18March Friday  19March Saturday  20March Sunday

User · Answer

Swift 3 Date extension  extension Date       var weekdayOrdinal  Int           return Calendar current component  weekday  from  self

User · Answer

There is an easier way  Just pass your string date to the following function  it will give you the day name     func getDayNameBy stringDate  String  - gt  String               let df    NSDateFormatter           df dateFormat    YYYY-MM-dd          let date   df dateFromString stringDate           df dateFormat    EEEE          return df stringFromDate date

User · Answer

You can use this table date formats for converting your date to different formats  My shortest code   func getDayOfWeek today  String  - gt  Int      let formatter NSDateFormatter   NSDateFormatter       formatter dateFormat    yyyy-MM-dd      let todayDate   formatter dateFromString today      formatter dateFormat    e      eeee  - gt  Friday     let weekDay   formatter stringFromDate todayDate       return Int weekDay     getDayOfWeek  2015-12-18      6

User · Answer

SWIFT 5 - Day of the week      extension Date            var dayofTheWeek  String                let dayNumber   Calendar current component  weekday  from  self                  day number starts from 1 but array count from 0              return daysOfTheWeek dayNumber - 1                     private var daysOfTheWeek   String                 return    Sun    Mon    Tue    Wed    Thu    Fri    Sat                      Date extension based on Fattie s answer

User · Answer

Swift 3   Xcode 8 helper function    func getDayOfWeek fromDate date  Date  - gt  String        let cal   Calendar identifier   gregorian      let dayOfWeek   cal component  weekday  from  date      switch dayOfWeek        case 1          return  Sunday      case 2          return  Monday      case 3          return  Tuesday      case 4          return  Wednesday      case 5          return  Thursday      case 6          return  Friday      case 7          return  Saturday      default          return nil

User · Answer

SWIFT 2 0 code to present the current week starting from monday    IBAction func show sender  AnyObject           Getting Days of week corresponding to their dateFormat      let calendar   NSCalendar currentCalendar       let dayInt  Int      var weekDate   String           var i   2      print  Dates corresponding to days are       while  dayInt - dayInt    i  lt  9                let weekFirstDate   calendar dateByAddingUnit  Day  value   -dayInt i   toDate  NSDate    options              let dateFormatter   NSDateFormatter           dateFormatter dateFormat    EEEE dd MMMM          let dayOfWeekString   dateFormatter stringFromDate weekFirstDate           weekDate append dayOfWeekString          i             for i in weekDate               print i    Printing the day stored in array             function to get week day func getDayOfWeek today String - gt Int        let formatter    NSDateFormatter       formatter dateFormat    MMM-dd-yyyy      let todayDate   formatter dateFromString today       let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian       let myComponents   myCalendar components  Weekday  fromDate  todayDate      let weekDay   myComponents weekday     return weekDay      IBAction func DateTitle sender  AnyObject             Getting currentDate and weekDay corresponding to it     let currentDate   NSDate       let dateFormatter   NSDateFormatter       dateFormatter dateFormat    MMM-dd-yyyy      let dayOfWeekStrings   dateFormatter stringFromDate currentDate      dayInt   getDayOfWeek dayOfWeekStrings

User · Answer

In my case I was after a three letter string for each day  I modified  Martin R s function as follows   func getDayOfWeekString today String - gt String        let formatter    NSDateFormatter       formatter dateFormat    yyyy-MM-dd      if let todayDate   formatter dateFromString today            let myCalendar   NSCalendar calendarIdentifier  NSCalendarIdentifierGregorian           let myComponents   myCalendar components  Weekday  fromDate  todayDate          let weekDay   myComponents weekday         switch weekDay           case 1              return  Sun          case 2              return  Mon          case 3              return  Tue          case 4              return  Wed          case 5              return  Thu          case 6              return  Fri          case 7              return  Sat          default              print  Error fetching days               return  Day                  else           return nil

[swift] Get day of week using NSDate

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