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 right locale hasn’t all the time been straightforward both. With iOS 15, Apple launched a brand new technique to convert Date objects from and to String. This new method 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 have to work with DateFormatter. As a substitute, we are able to ask a date to format itself primarily based on our necessities in a extra performant, simpler to make use of method.

On this put up 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 technique 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 machine 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’d need to have our date formatted as Could 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 totally different formatters.

For instance, when sending a Date to a server, we’ll usually have to ship our dates as ISO8601 compliant strings. Earlier than I clarify the code you simply noticed, I need to present you the right 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 varied capabilities on the thing that’s returned by the .datetime static property to pick out 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 are able to select the .broad formatting to spell out the total month identify. We might use .slender 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.

When you 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 all the time mechanically respect your consumer’s locale which is actually handy.

One other technique 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: .normal) // Thursday, Could 26, 2022, 8:15:28 PM

The above offers a really verbose formatted string. We will 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 through the use of the .omitted possibility:

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

There are tons of various combos you possibly can provide you with 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 possibly can cowl the widespread 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 will 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 = "Could 26, 2022, 8:30 PM"
let expectedFormat = Date.FormatStyle()
    .month().12 months().day()
    .hour().minute()
let date = strive! Date(string, technique: expectedFormat)

The order of our date elements doesn’t matter; they are going to mechanically be rearranged to match the consumer’s locale. That is tremendous highly effective, however it does imply that we are able to’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 need to use iOS 15’s FormatStyle to work format Date objects. You noticed the right way to go from Date to String, and the opposite method round. Whereas FormatStyle is extra handy than DateFormatter, it’s iOS 15 solely. So in the event you’re nonetheless supporting iOS 14 you’ll need to be certain that to take a look at DateFormatter too.