iOS Swift - Get the Current Local Time and Date Timestamp

Question

I'm trying to make an attendance app and I am really confused about date and time in iOS and Firebase.

I use date as Key, this is the structure of my Firebase database.

--Employees
  --Unique_ID
     --Details
          Name: John
     --Attendance
          --dateToday
              Timein: 8:00 AM
              Timeout: 5:00 PM
              BreakStart: 12:00 PM
              BreakFinish: 1:00 PM

This is my code to get the date timestamp I used as Key

 override func viewDidLoad() {
     super.viewDidLoad()

     let now = NSDate()
     let nowTimeStamp = self.getCurrentTimeStampWOMiliseconds(dateToConvert: now)

     // I save this dateToday as Key in Firebase
     dateToday = nowTimeStamp
}


func getCurrentTimeStampWOMiliseconds(dateToConvert: NSDate) -> String {
    let objDateformat: DateFormatter = DateFormatter()
    objDateformat.dateFormat = "yyyy-MM-dd"
    let strTime: String = objDateformat.string(from: dateToConvert as Date)
    let objUTCDate: NSDate = objDateformat.date(from: strTime)! as NSDate
    let milliseconds: Int64 = Int64(objUTCDate.timeIntervalSince1970)
    let strTimeStamp: String = "\(milliseconds)"
    return strTimeStamp
}

But when I convert it back to date I get 2017-09-22 16:00:00 +0000, which is wrong because it is 23rd of September in my location.

What is the right code to use so that I can get the correct date timestamp and time timestamp?

Solution 1

For saving Current time to firebase database I use Unic Epoch Conversation:

let timestamp = NSDate().timeIntervalSince1970

and For Decoding Unix Epoch time to Date().

let myTimeInterval = TimeInterval(timestamp)
let time = NSDate(timeIntervalSince1970: TimeInterval(myTimeInterval))

Solution 2

If you just want the unix timestamp, create an extension:

extension Date {
    func currentTimeMillis() -> Int64 {
        return Int64(self.timeIntervalSince1970 * 1000)
    }
}

Then you can use it just like in other programming languages:

let timestamp = Date().currentTimeMillis()

Solution 3

in Swift 5

extension Date {
    static var currentTimeStamp: Int64{
        return Int64(Date().timeIntervalSince1970 * 1000)
    }
}

call like this:

let timeStamp = Date.currentTimeStamp
print(timeStamp)

Thanks @lenooh

Solution 4

The simple way to create Current TimeStamp. like below,

func generateCurrentTimeStamp () -> String {
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy_MM_dd_hh_mm_ss"
    return (formatter.string(from: Date()) as NSString) as String
}

Solution 5

If you code for iOS 13.0 or later and want a timestamp, then you can use:

let currentDate = NSDate.now

View more solutions

Comments

[barrylachapelle]

By far the best answer.

[Spire]

will NSDate().timeIntervalSince1970 be calculating the timezone, or is there any way to do this for different timezones?

[Andrew Koster]

Epoch time, by definition, is in UTC. It's the number of seconds/milliseconds elapsed since midnight on January 1, 1970, in the UTC timezone. Time zone information would only be useful for displaying it in a specific human language, not for storing or calculating anything.

[djdance]

this is not 10-digit timestamp