Get UTC time and local time from NSDate object

Question

In objective-c  the following code results in the UTC date time information using the date API   NSDate  currentUTCDate    NSDate date    In Swift however   let date   NSDate date     results in local date and time   I have two questions    How can I get UTC time and local time  well date gives local time  in NSDate objects  How can I get precision for seconds from the NSDate object    EDIT 1  Thanks for all the inputs but I am not looking for NSDateFormatter objects or string values  I am simply looking for NSDate objects  however we cook them up but that s the requirement   See point 1

User · Answer

let date   Date    print date     printed date is UTC       If you are using playground  use a print statement to check the time   Playground shows local time until you print it  Do not depend on the right side panel of playground       This code gives date in UTC  If you need the local time  you should call the following extension with timezone as Timezone current   extension Date       var currentUTCTimeZoneDate  String           let formatter   DateFormatter           formatter timeZone   TimeZone identifier   UTC           formatter amSymbol    AM          formatter pmSymbol    PM          formatter dateFormat    yyyy-MM-dd HH mm ss           return formatter string from  self            For UTC time  use it like  Date   currentUTCTimeZoneDate

User · Answer

a date is independant of any timezone  so use a Dateformatter and attach a timezone for display   swift   let date   NSDate   let dateFormatter   NSDateFormatter   let timeZone   NSTimeZone name   UTC    dateFormatter timeZone   timeZone  println dateFormatter stringFromDate date     objC   NSDate  date    NSDate date   NSDateFormatter  dateFormatter     NSDateFormatter alloc  init   NSTimeZone  timeZone    NSTimeZone timeZoneWithName   UTC      dateFormatter setTimeStyle NSDateFormatterMediumStyle    dateFormatter setDateStyle NSDateFormatterMediumStyle    dateFormatter setTimeZone timeZone          NSLog         dateFormatter stringFromDate date

User · Answer

NSDate is a specific point in time without a time zone  Think of it as the number of seconds that have passed since a reference date  How many seconds have passed in one time zone vs  another since a particular reference date  The answer is the same   Depending on how you output that date  including looking at the debugger   you may get an answer in a different time zone   If they ran at the same moment  the values of these are the same  They re both the number of seconds since the reference date  which may be formatted on output to UTC or local time  Within the date variable  they re both UTC   Objective-C   NSDate  UTCDate    NSDate date    Swift   let UTCDate   NSDate date     To explain this  we can use a NSDateFormatter in a playground   import UIKit  let date   NSDate date           Jul 23  2014  11 01 AM   lt -- looks local without seconds  But   var formatter   NSDateFormatter   formatter dateFormat    yyyy-MM-dd HH mm ss ZZZ  let defaultTimeZoneStr   formatter stringFromDate date          2014-07-23 11 01 35 -0700   lt -- same date  local  but with seconds formatter timeZone   NSTimeZone abbreviation   UTC   let utcTimeZoneStr   formatter stringFromDate date          2014-07-23 18 01 41  0000   lt -- same date  now in UTC   The date output varies  but the date is constant  This is exactly what you re saying  There s no such thing as a local NSDate   As for how to get microseconds out  you can use this  put it at the bottom of the same playground    let seconds   date timeIntervalSince1970 let microseconds   Int seconds   1000    1000    chops off seconds   To compare two dates  you can use date compare otherDate

User · Answer

Swift 3  You can get Date based on your current timezone from UTC  extension Date       func currentTimeZoneDate   - gt  String           let dtf   DateFormatter           dtf timeZone   TimeZone current         dtf dateFormat    yyyy-MM-dd HH mm ss           return dtf string from  self            Call like this   Date   currentTimeZoneDate

User · Answer

At the moment  with the latest changes to Swift   NSDate date   is not longer available        Instead you just need to initialize NSDate and it gets the current date and time  To try it  in a playground       var d   NSDate   d   and you will get    Oct 22  2014  12 20 PM

User · Answer

I found an easier way to get UTC in Swift4  Put this code in playground  let date   Date        Mar 15  2018 at 4 01 PM    let dateFormatter   DateFormatter   dateFormatter dateFormat    yyyy-MM-dd HH mm ss ZZZ  dateFormatter timeZone   TimeZone secondsFromGMT  0   let newDate   dateFormatter string from  date       2018-03-15 21 05 04  0000

User · Answer

The documentation says that the date method returns a new date set to the current date and time regardless of the language used  The issue probably sits somewhere where you present the date using NSDateFormatter  NSDate is just a point on a time line  There is no time zones when talking about NSDate  I made a test  Swift print NSDate     Output  2014-07-23 17 56 45  0000 Objective-C NSLog   quot    quot    NSDate date     Output  2014-07-23 17 58 15  0000 Result - No difference

User · Answer

In addition to other answers  you can write an extension for Date class to get formatted Data in specific TimeZone to make it as utility function for future use  Like   extension Date     func dateInTimeZone timeZoneIdentifier  String  dateFormat  String  - gt  String     let dtf   DateFormatter    dtf timeZone   TimeZone identifier  timeZoneIdentifier   dtf dateFormat   dateFormat   return dtf string from  self         Now you can call it like   Date   dateInTimeZone timeZoneIdentifier   UTC   dateFormat   yyyy-MM-dd HH mm ss

User · Answer

Xcode 9     Swift 4   also works Swift 3 x   extension Formatter          create static date formatters for your date representations     static let preciseLocalTime  DateFormatter             let formatter   DateFormatter           formatter locale   Locale identifier   en US POSIX           formatter dateFormat    HH mm ss SSS          return formatter             static let preciseGMTTime  DateFormatter             let formatter   DateFormatter           formatter locale   Locale identifier   en US POSIX           formatter timeZone   TimeZone secondsFromGMT  0          formatter dateFormat    HH mm ss SSS          return formatter               extension Date          you can create a read-only computed property to return just the nanoseconds from your date time     var nanosecond  Int   return Calendar current component  nanosecond   from  self             the same for your local time     var preciseLocalTime  String           return Formatter preciseLocalTime string for  self                     or GMT time     var preciseGMTTime  String           return Formatter preciseGMTTime string for  self                    Playground testing  Date   preciseLocalTime     09 13 17 385   GMT-3 Date   preciseGMTTime       12 13 17 386   GMT Date   nanosecond          386268973   This might help you also formatting your dates

User · Answer

My Xcode Version 6 1 1  6A2008a   In playground  test like this      I m in East Timezone 8 let x   NSDate     Output  Dec 29  2014  11 37 AM  let y   NSDate init     Output  Dec 29  2014  11 37 AM  println x    Output  2014-12-29 03 37 24  0000       seconds since 2001 x hash   Output 441 517 044 x hashValue   Output 441 517 044 x timeIntervalSinceReferenceDate   Output 441 517 044 875367     seconds since 1970 x timeIntervalSince1970   Output 1 419 824 244 87537

[ios] Get UTC time and local time from NSDate object

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