Formatting dates in Swift utilizing Date.FormatStyle on iOS 15 – Donny Wals

Working with dates isn’t simple. And displaying them to your customers within the right locale hasn’t all the time been simple both. With iOS 15, Apple launched a brand new strategy to convert Date objects from and to String. This new manner comes within the type of the brand new Formatter api that replaces DateFormatter.

As any seasoned iOS developer will let you know, DateFormatter objects are costly to create, and therefor sort of tedious to handle appropriately. With the brand new Formatter api, we not must work with DateFormatter. As an alternative, we are able to ask a date to format itself based mostly on our necessities in a extra performant, simpler to make use of manner.

On this submit I’ll present you how one can convert Date objects to String in addition to how one can extract a Date from a String.

Changing a Date to a String

Essentially the most simple strategy to convert a Date to a String is the next:

let formatted = Date().formatted() // 5/26/2022, 7:52 PM

By default, the formatted() perform makes use of a compact configuration for our String. The way in which formatted() converts our Date to String takes under consideration the consumer’s present locale. For instance, if my machine was set to be in Dutch, the date could be formatted as 26-5-2022 19:54 which is a extra applicable formatting for the Dutch language.

Nevertheless, this may not all the time be what we want. For instance, we would need to have our date formatted as Might 26 2022, 7:52 PM. We are able to use the next code to do this:

let formatted = Date().formatted(
    .dateTime
        .day().month(.huge).yr()
        .hour().minute()
)

Let’s break this code aside a bit. The formatted perform takes an object that conforms to the FormatStyle protocol as its argument. There are numerous methods for us to create such an object. The FormatStyle protocol has a number of handy extensions that may present us with a number of completely different formatters.

For instance, when sending a Date to a server, we’ll typically must ship our dates as ISO8601 compliant strings. Earlier than I clarify the code you simply noticed, I need to present you methods to seize an ISO8601 compliant string from the present Date.

let formatted = Date().formatted(.iso8601) // 2022-05-26T18:06:55Z

Neat, huh?

Okay, again to the instance from earlier than. The .datetime formatter is used as a foundation for our customized formatting. We are able to name varied capabilities on the thing that’s returned by the .datetime static property to pick out the data that we need to present.

A few of these properties, just like the month, will be configured to specify how they need to be formatted. Within the case of .month, we are able to select the .huge formatting to spell out the total month identify. We might use .slim to abbreviate the month right down to a single letter, or we might use one of many different choices to signify the month in numerous methods.

In the event you omit a property, like for instance .yr(), our formatted date will omit the yr that’s embedded within the Date. And once more, the underlying formatter will all the time robotically respect your consumer’s locale which is absolutely handy.

One other strategy to format the date is to by specifying the way you need the date and time to be formatted respectively:

let formatted = Date().formatted(date: .full, time: .commonplace) // Thursday, Might 26, 2022, 8:15:28 PM

The above offers a really verbose formatted string. We are able to make a extra compact one utilizing the next settings:

let formatted = Date().formatted(date: .abbreviated, time: .shortened) // Might 26, 2022, 8:16 PM

It’s even potential to omit the date or time solely through the use of the .omitted possibility:

let formatted = Date().formatted(date: .abbreviated, time: .omitted) // Might 26, 2022

There are tons of various mixtures you may provide you with so I extremely advocate you discover this api some extra to get a way of how versatile it truly is.

Making a Date from a String

Changing String to Date is barely much less handy than going from a Date to a String but it surely’s nonetheless not too dangerous. Right here’s how you may cowl the frequent case of changing an ISO8601 compliant string to a Date:

let string = "2022-05-26T18:06:55Z"
let expectedFormat = Date.ISO8601FormatStyle()
let date = strive! Date(string, technique: expectedFormat)

We make use of the Date initializer that takes a string and a formatting technique that’s used to parse the string.

We are able to additionally use and configure an occasion of FormatStyle to specify the elements that we anticipate to be current in our date string and let the system parse it utilizing the consumer’s locale:

let string = "Might 26, 2022, 8:30 PM"
let expectedFormat = Date.FormatStyle()
    .month().yr().day()
    .hour().minute()
let date = strive! Date(string, technique: expectedFormat)

The order of our date elements doesn’t matter; they may robotically be rearranged to match the consumer’s locale. That is tremendous highly effective, but it surely does imply that we are able to’t use this to parse dates on gadgets that use a distinct locale than the one which matches the string’s locale. The perfect locale agnostic date string is ISO8601 so in case you have management over the date strings that you simply’ll parse, be sure you use ISO8601 when potential.

Abstract

On this quick article, you realized how you should use iOS 15’s FormatStyle to work format Date objects. You noticed methods to go from Date to String, and the opposite manner round. Whereas FormatStyle is extra handy than DateFormatter, it’s iOS 15 solely. So if you happen to’re nonetheless supporting iOS 14 you’ll need to make certain to take a look at DateFormatter too.