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

Working with dates isn’t straightforward. And displaying them to your customers within the appropriate locale hasn’t at all times been straightforward both. With iOS 15, Apple launched a brand new approach to convert Date objects from and to String. This new means 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 a substitute, we will ask a date to format itself based mostly on our necessities in a extra performant, simpler to make use of means.

On this publish 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 approach 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 best way formatted() converts our Date to String takes under consideration the consumer’s present locale. For instance, if my gadget was set to be in Dutch, the date can be formatted as 26-5-2022 19:54 which is a extra applicable formatting for the Dutch language.

Nonetheless, this may not at all times be what we want. For instance, we’d wish to have our date formatted as Might 26 2022, 7:52 PM. We will use the next code to try this:

let formatted = Date().formatted(
    .dateTime
        .day().month(.broad).12 months()
        .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 wish to present you the way 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 will name numerous features on the article that’s returned by the .datetime static property to pick out the knowledge that we wish 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 will select the .broad formatting to spell out the complete month identify. We may use .slender to abbreviate the month all the way down to a single letter, or we may use one of many different choices to signify the month in several methods.

If you happen to omit a property, like for instance .12 months(), our formatted date will omit the 12 months that’s embedded within the Date. And once more, the underlying formatter will at all times routinely respect your consumer’s locale which is basically handy.

One other approach 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 gives a really verbose formatted string. We will 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 attainable to omit the date or time fully through the use of the .omitted possibility:

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

There are tons of various combos you might give you so I extremely suggest 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 however it’s nonetheless not too unhealthy. Right here’s how you might 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 = attempt! 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 will additionally use and configure an occasion of FormatStyle to specify the parts 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().12 months().day()
    .hour().minute()
let date = attempt! Date(string, technique: expectedFormat)

The order of our date parts doesn’t matter; they’ll routinely be rearranged to match the consumer’s locale. That is tremendous highly effective, however it does imply that we will’t use this to parse dates on gadgets that use a distinct locale than the one which matches the string’s locale. The most effective locale agnostic date string is ISO8601 so you probably have management over the date strings that you just’ll parse, be sure to use ISO8601 when attainable.

Abstract

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