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

Working with dates isn’t simple. And exhibiting them to your customers within the right locale hasn’t all the time been simple both. With iOS 15, Apple launched a brand new solution 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 form of tedious to handle appropriately. With the brand new Formatter api, we now not must work with DateFormatter. As an alternative, we will 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 easy solution to convert a Date to a String is the next:

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

By default, the formatted() operate makes use of a compact configuration for our String. The best way formatted() converts our Date to String takes into 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 acceptable formatting for the Dutch language.

Nonetheless, this won’t all the time be what we’d like. For instance, we would need to have our date formatted as Could 26 2022, 7:52 PM. We are able to use the next code to do this:

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

Let’s break this code aside a bit. The formatted operate 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 usually 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 numerous capabilities on the thing that’s returned by the .datetime static property to pick the knowledge that we need to present.

A few of these properties, just like the month, may be configured to specify how they need to be formatted. Within the case of .month, we will select the .extensive formatting to spell out the complete month identify. We might use .slender to abbreviate the month all the way down to a single letter, or we might use one of many different choices to signify the month in numerous methods.

If you happen to 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 mechanically respect your consumer’s locale which is admittedly handy.

One other solution 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, Could 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) // Could 26, 2022, 8:16 PM

It’s even potential to omit the date or time fully by utilizing the .omitted possibility:

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

There are tons of various combos you can 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 unhealthy. Right here’s how you can 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 parts that we count on to be current in our date string and let the system parse it utilizing the consumer’s locale:

let string = "Could 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 parts doesn’t matter; they’ll mechanically be rearranged to match the consumer’s locale. That is tremendous highly effective, but it surely does imply that we will’t use this to parse dates on gadgets that use a unique locale than the one which matches the string’s locale. One of the best locale agnostic date string is ISO8601 so when you have management over the date strings that you just’ll parse, be sure to use ISO8601 when potential.

Abstract

On this brief article, you realized how you should utilize 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 for those who’re nonetheless supporting iOS 14 you’ll need to be certain to take a look at DateFormatter too.