Convert timestamp from Firebase to readable date

Question

I would like to convert a timestamp posted in firebase to readable data. I am able to read the timestamp, but not able to convert it, or append it to an array.
This is my progress:
var orderDateHistoryArray = [String:Int]()
func getOrderDates() {

let uid = Auth.auth().currentUser!.uid
    let orderDateHistoryRef = Database.database().reference().child("users/\(uid)/Orders/")
    orderDateHistoryRef.observeSingleEvent(of: .value, with: { (snapshot) in

let value = snapshot.value as? NSDictionary
        if  let orderDate = value?["Date"] as? [Int:String] {
           self.orderDateHistoryArray += Array(orderDate.values).map{ Date(timeIntervalSince1970: TimeInterval($0/1000))} // This fails. Error: "Binary operator '/' cannot be applied to operands of type 'String' and 'Int'"

print(orderDate) 
        }
        self.tableView.reloadData()
        // ...
    }) { (error) in
        print(error.localizedDescription)
    }
}
}
The print(orderDate) statement prints correctly:
```
"["-LQYspEghK3KE27MlFNE": 1541421618601,
“-LQsYbhf-vl-NnRLTHhK”: 1541768379422,
“-LQYDWAKlzTrlTtO1Qiz”: 1541410526186,
“-LQsILjpNqKwLl9XBcQm”: 1541764115618]"
```
This is childByAutoID : timeInMilliseconds
So, I want to read out the timeInMilliseconds , convert it to a readable timestamp and append it to the orderDateHistoryArray

Caleb Kleveter · Accepted Answer

First, you will need to convert the timestamps to Date (https://developer.apple.com/documentation/foundation/date) instances. Timestamps are usually seconds since 12:00AM, January 1st, 1970, so you would use the init(timeIntervalSince1970:) initializer:
swift
let timestamp: TimeInterval = 1541764115618
let date = Date(timeIntervalSince1970: timestamp)

You can then create a human readable string from that Date instance using DateFormatter (https://developer.apple.com/documentation/foundation/dateformatter). DateFormatter uses strings with special placeholders to format the date's components the way you want it:
This is how you create the formatter:
swift
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: .iso8601)
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "h:mma, MMMM d, yyyy"

You can then format the date like this:
swift
let readable = formatter.string(from: date)

If you want to mess around with date formats, I recommend this site: http://nsdateformatter.com/

Stian Andreassen · Answer

$0/1000 seems to be trying to divide a string by and int. So maybe parse it into an int first.
I absolutely agree, but I have not been able to parse to int. Any suggestions?
I also don't understand what the ultimate goal is. Do you want to print out a specific date time like "1:00PM January 1st, >2018" or do you want to print out time elapsed like "4 minutes, 32 seconds and counting..."?
The goal is like you suggested: 
date time like "1:00PM January 1st, >2018"
Thank you

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Stian Andreassen

Stian Andreassen

Convert timestamp from Firebase to readable date

Brendan Whiting

Brendan Whiting

2 Answers

Caleb Kleveter

Caleb Kleveter

Stian Andreassen

Stian Andreassen