let isoFormatter = ISO8601DateFormatter() // Example 1: Using ISO8601 date formatter with date string that ends with whole seconds let dateStringSeconds = "2021-10-06T11:27:55Z" let newDateSec = isoFormatter.date(from: dateStringSeconds) print(String(describing: newDateSec)) // 2021-10-06 11:27:55 +0000 // Example 2: Using ISO8601 date formatter with date string that ends with milliseconds let dateStringMilliSeconds = "2021-10-06T11:27:55.341Z" isoFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds] let newDateMilli = isoFormatter.date(from: dateStringMilliSeconds) print(String(describing: newDateMilli)) // 2021-10-06 11:27:55 +0000