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swiftlocalization

How to allow user to specify currency format in Swift

I'm curious, does anyone have suggestions on how to give users control over the conversion of Double/Float to a currency value using the formatted methods introduced in WWDC21 What's new in Foundation video?

Here's the code snippet from the video:

    let price = 29
    let priceFormatted = price.formatted(.currency(code: "usd"))
    // priceFormatted is "$29.00"
    print(priceFormatted)

I would like to give the user an interface that lets them choose between a default that the OS supplies based on device settings, and choosing something specific (eg Japanese Yen). So I guess that boils down to two things:

  1. What is the list of codes that the .currency(code:) method can take? I’d also like it if there was some API that gave me a mapping from codes (eg “usd”) to localized label I can present the user (eg “U.S. Dollars” in English).

  2. How do I ask the OS for the code that would be the default for the locale settings?

Solution

  • Localised currency information is encapsulated by the Currency structure in Foundation.

    A list of the standard currencies (conforming to ISO 4217) can be accessed using Locale.Currency.isoCurrencies. But as that list is probably too exhaustive, you might prefer to use Locale.commonISOCurrencyCodes which has roughly half the entries (156 vs 304 at this time).

    You can get a localised label for each code using the localizedString(forCurrencyCode:) method on a given Locale.

    Finally, you can get the default currency code for your device's settings using:

     let defaultCurrencyCode = Locale.current.currency?.identifier

    Kudos to @HangarRash for his quick response!