What's new with FormatStyles in iOS 16

Another year, another WWDC. The yearly developer conference was firing on all cylinders this year, with some nice additions and one big fix on the FormatStyle front.

This only scratches the surface on the topic! I built a whole website to cover format styles in excruciating detail: fuckingformatstyle.com/goshdarnformatstyle.com

See some examples as a Gist

1. ByteCountFormatStyle Doesn’t Crash Anymore

The first good news is that Apple has fixed an issue I found in my research.

The formatter gives you the ability to take a byte count and convert to other orders of magnatude. For example, you could take a count in kilobytes and convert it to terabytes.

Previously, converting any count to any unit of gigabyte or above would result in a fatalError crash:

// .gb, .tb, .pb, .eb, .zb, and .ybOrHigher cause a FatalError (Feedback FB10031442)
terabyte.formatted(.byteCount(style: .file, allowedUnits: .gb))

I’m happy to report that as of 14.0 beta (14A5228q), this now works as expected.

terabyte.formatted(.byteCount(style: .file, allowedUnits: .gb)) // "1,000 GB"

2. New Measurement style for UnitInformatStorage

I mentioned on the gosh darned site that you could use the Measurement format style to convert between units. The issue is that you aren’t able the same customization options as the ByteCountFormatStyle using that option.

That’s changed now.

We now have an API for the byte count format style on top of the Measurement framework when using the UnitInformationStorage unit.

let severalTerabytes = Measurement(value: 3, unit: UnitInformationStorage.terabytes)

severalTerabytes.formatted() // "3 TB"
severalTerabytes.formatted(.byteCount(style: .binary)) // "2.73 TB"
severalTerabytes.formatted(.byteCount(style: .decimal)) // "3 TB"
severalTerabytes.formatted(.byteCount(style: .file)) // "3 TB"
severalTerabytes.formatted(
    .byteCount(
        style: .binary,
        allowedUnits: .tb,
        spellsOutZero: true,
        includesActualByteCount: true
    )
) // "2.73 TB (3,000,000,000,000 bytes)"
severalTerabytes.formatted(
    .byteCount(
        style: .binary,
        allowedUnits: .tb,
        spellsOutZero: true,
        includesActualByteCount: false
    )
) // "2.73 TB"

severalTerabytes.formatted(
    .byteCount(
        style: .binary,
        allowedUnits: .tb,
        spellsOutZero: true,
        includesActualByteCount: true
    )
    .locale(Locale(identifier: "fr_FR"))
) // "2,73 To (3 000 000 000 000 octets)"

severalTerabytes.formatted(
    .byteCount(
        style: .binary,
        allowedUnits: .tb,
        spellsOutZero: true,
        includesActualByteCount: true
    )
    .attributed
)

let byteCountMeasurementStyle = Measurement<UnitInformationStorage>.FormatStyle.ByteCount(
    style: .binary,
    allowedUnits: .mb,
    spellsOutZero: true,
    includesActualByteCount: true,
    locale: Locale(identifier: "fr_FR")
)

severalTerabytes.formatted(byteCountMeasurementStyle) // "2 861 022,9 Mo (3 000 000 000 000 octets)"

// This no longer results in a crash.
let threeTerabytes = Int64(3_000_000_000_000)
threeTerabytes.formatted(
    .byteCount(
        style: .binary,
        allowedUnits: .tb,
        spellsOutZero: false,
        includesActualByteCount: true
    )
) // "2.73 TB (3,000,000,000,000 bytes)"

Very handy.

3. New `Duration` Unit Support

iOS 16 introduces the new Duration unit, which is purpose built to deal with very accurate time measurements. There’s two new styles to support it.

TimeFormatStyle

The simpler of the two, this one is the default

let coupleOfSeconds: Duration = .seconds(3)

With it, they’ve added a new build in format style to allow us to output the values in a nice way:

let thousandSeconds: Duration = .seconds(1000)

thousandSeconds.formatted() // "0:16:40"
thousandSeconds.formatted(.time(pattern: .hourMinute)) // "0:17"
thousandSeconds.formatted(.time(pattern: .hourMinute).locale(Locale(identifier: "fr_FR"))) // "0:17"
thousandSeconds.formatted(.time(pattern: .hourMinute(padHourToLength: 10, roundSeconds: .awayFromZero))) // "0,000,000,000:17"
thousandSeconds.formatted(.time(pattern: .hourMinuteSecond)) // "0:16:40"
thousandSeconds.formatted(.time(pattern: .hourMinuteSecond(padHourToLength: 3, fractionalSecondsLength: 3,  roundFractionalSeconds: .awayFromZero))) // "000:16:40.000"
thousandSeconds.formatted(.time(pattern: .minuteSecond)) // "16:40"
thousandSeconds.formatted(.time(pattern: .minuteSecond(padMinuteToLength: 3, fractionalSecondsLength: 3, roundFractionalSeconds: .awayFromZero))) // "016:40.000"

UnitsFormatStyle

You can also use the UnitsFormatStyle to show the Duration as a different unit.

let halfSecond: Duration = .milliseconds(500)
halfSecond.formatted(.units()) // "0 sec"
halfSecond.formatted(
    .units(allowed: [.milliseconds])
) // "500 ms"
halfSecond.formatted(
    .units(
        allowed: [.milliseconds],
        width: .abbreviated
    )
) // "500 ms"
halfSecond.formatted(
    .units(
        allowed: [.milliseconds],
        width: .condensedAbbreviated
    )
) // "500ms"
halfSecond.formatted(
    .units(
        allowed: [.milliseconds],
        width: .narrow
    )
)
halfSecond.formatted(
    .units(
        allowed: [.milliseconds],
        width: .wide
    )
) // "500 milliseconds"
halfSecond.formatted(
    .units(
        allowed: [.seconds, .milliseconds],
        width: .wide,
        maximumUnitCount: 2,
        zeroValueUnits: .show(length: 2),
        valueLength: 5,
        fractionalPart: .show(length: 2, rounded: .awayFromZero, increment: 0.000025)
    )
) // "00,000.000000 seconds, 00,500.000000 milliseconds"

4. URL Support

There’s a new, and surprisingly deep, format style for URLs that start simple:

let appleURL = URL(string: "https://apple.com")!
appleURL.formatted() // "https://apple.com"
appleURL.formatted(.url) // "https://apple.com"
appleURL.formatted(.url.locale(Locale(identifier: "fr_FR"))) // "https://apple.com"

And quickly descend into some nice complexity:

var httpComponents = URLComponents(url: appleURL, resolvingAgainstBaseURL: false)!
httpComponents.scheme = "https"
httpComponents.user = "jAppleseed"
httpComponents.password = "Test1234"
httpComponents.host = "apple.com"
httpComponents.port = 80
httpComponents.path = "/macbook-pro"
httpComponents.query = "get-free"
httpComponents.fragment = "someFragmentOfSomething"

let complexURL = httpComponents.url!
let everythingStyle = URL.FormatStyle(
    scheme: .always,
    user: .always,
    password: .always,
    host: .always,
    port: .always,
    path: .always,
    query: .always,
    fragment: .always
)

everythingStyle.format(complexURL) // "https://jAppleseed:Test1234@apple.com:80/macbook-pro?get-free#someFragmentOfSomething"

let omitStyle = URL.FormatStyle(
    scheme: .omitIfHTTPFamily,
    user: .omitIfHTTPFamily,
    password: .omitIfHTTPFamily,
    host: .omitIfHTTPFamily,
    port: .omitIfHTTPFamily,
    path: .omitIfHTTPFamily,
    query: .omitIfHTTPFamily,
    fragment: .omitIfHTTPFamily
)

var httpsComponent = httpComponents
httpsComponent.scheme = "https"
let httpsURL = httpsComponent.url!

var ftpComponents = httpComponents
ftpComponents.scheme = "ftp"
let ftpURL = ftpComponents.url!

omitStyle.format(complexURL) // ""
omitStyle.format(httpsURL) // ""
omitStyle.format(ftpURL) // "ftp://jAppleseed@apple.com:80/macbook-pro?get-free#someFragmentOfSomething"

5. Date.VerbatimFormatStyle Changes

There’s a couple of significant changes to the Verbatim style.

The style can now have the locale set.
You can access it using the .verbatim() extension on FormatStyle

let twosday = Calendar(identifier: .gregorian).date(from: twosdayDateComponents)!

twosday.formatted(
    .verbatim(
        "\(hour: .defaultDigits(clock: .twentyFourHour, hourCycle: .oneBased)):\(minute: .defaultDigits):\(minute: .defaultDigits) \(dayPeriod: .standard(.wide))",
        locale: Locale(identifier: "zh_CN"),
        timeZone: .current,
        calendar: .current
    )
) // "2:22:22 上午"