Formatting UTC and Local Dates in Swift

This post presents a series of code snippets for parsing and formatting UTC and local Dates in Swift.

UTC Date Format

Use DateFormatter to parse and format a date in Swift. The default time zone for a DateFormatter is the device’s local time, so to obtain UTC time the timeZone value needs to be configured.

let utcDateFormatter = DateFormatter()
utcDateFormatter.dateStyle = .medium
utcDateFormatter.timeStyle = .medium

// The default timeZone on DateFormatter is the device’s 
// local time zone. Set timeZone to UTC to get UTC time.
utcDateFormatter.timeZone = TimeZone(abbreviation: "UTC")

// Printing a Date
let date = Date()
print(utcDateFormatter.string(from: date))

// Parsing a string representing a date
let dateString = "May 31, 2020 at 4:32:27 AM"
let utcDate = utcDateFormatter.date(from: dateString)

Local Timezone Date Format

No configuration is required for a DateFormatter to parse and format a date in local time.

let localDateFormatter = DateFormatter()
localDateFormatter.dateStyle = .medium
localDateFormatter.timeStyle = .medium

// No timeZone configuration is required to obtain the 
// local time from DateFormatter.

// Printing a Date
let date = Date()
print(localDateFormatter.string(from: date))

// Parsing a string representing a date
let dateString = "May 30, 2020 at 11:32:27 PM"
let localDate = localDateFormatter.date(from: dateString)

Date Formatting With ISO8601DateFormatter, UTC Timezone

ISO8601DateFormatter is a special DateFormatter for parsing timestamps in ISO8601 format. For example, 2020-05-31T04:32:27Z. By default, ISO8601DateFormatter is configured to parse and format dates in UTC.

// The default timeZone for ISO8601DateFormatter is UTC
let utcISODateFormatter = ISO8601DateFormatter()

// Printing a Date
let date = Date()
print(utcISODateFormatter.string(from: date))

// Parsing a string timestamp representing a date
let dateString = "2020-05-31T04:32:27Z"
let utcDate = utcISODateFormatter.date(from: dateString)

Date Formatting With ISO8601DateFormatter, Local Timezone

To use a ISO8601DateFormatter to parse and format local time, set the timeZone parameter to TimeZone.current.

// The default timeZone on ISO8601DateFormatter is UTC.
// Set timeZone to UTTimeZone.current to get local time.
let localISOFormatter = ISO8601DateFormatter()
localISOFormatter.timeZone = TimeZone.current

// Printing a Date
let date = Date()
print(localISOFormatter.string(from: date))

// Parsing a string timestamp representing a date
let dateString = "2020-05-30T23:32:27-05:00"
let localDate = localISOFormatter.date(from: dateString)

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Date Formatting in Swift

That’s it! Configuring DateFormatter and ISO8601DateFormatter will allow you to parse and format dates in Swift.