ISO8601DateFormatter doesn't parse ISO date string

Question

I'm trying to parse this

2017-01-23T10:12:31.484Z

using native ISO8601DateFormatter class provided by iOS 10 but always fails. If the string not contains milliseconds, the Date object is created without problems.

I'm tried this and many options combination but always fails...

let formatter = ISO8601DateFormatter() formatter.timeZone = TimeZone(secondsFromGMT: 0) formatter.formatOptions = [.withInternetDateTime, .withDashSeparatorInDate, .withColonSeparatorInTime, .withColonSeparatorInTimeZone, .withFullTime] 

Any idea? Thanks!

Answer 1

Prior to macOS 10.13 / iOS 11 ISO8601DateFormatter does not support date strings including milliseconds.

A workaround is to remove the millisecond part with regular expression.

let isoDateString = "2017-01-23T10:12:31.484Z" let trimmedIsoString = isoDateString.replacingOccurrences(of: "\\.\\d+", with: "", options: .regularExpression) let formatter = ISO8601DateFormatter() let date = formatter.date(from: trimmedIsoString) 

In macOS 10.13+ / iOS 11+ a new option is added to support fractional seconds:

static var withFractionalSeconds: ISO8601DateFormatter.Options { get }

let isoDateString = "2017-01-23T10:12:31.484Z" let formatter = ISO8601DateFormatter() formatter.formatOptions =  [.withInternetDateTime, .withFractionalSeconds] let date = formatter.date(from: isoDateString) 

Answer 2

For people that are not ready to go to iOS 11 yet, you can always create your own formatter to handle milliseconds, e.g.:

extension DateFormatter {     static var iSO8601DateWithMillisec: DateFormatter {         let dateFormatter = DateFormatter()         dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"         return dateFormatter     } } 

Usage:

let formater = DateFormatter.iSO8601DateWithMillisec let date = formater.date(from: "2017-01-23T10:12:31.484Z")! print(date) // output: 2017-01-23 10:12:31 +0000 

It is slightly more elegant than writing a regex to strip out the milliseconds from the input string.