Swift show price depends on Locale

Question

I am getting a string value that represents a price. I want to convert it to another string with specific precision and format it according to a current device Locale.

Decimal(string: "123,4567", locale: NSLocale.current)?.formatted(.number.precision(.fractionLength(precision)))

This code works for the german language and the output is "123,45". But if I switch to English the output is "123.00". The problem is with the dot instead of the comma. Any ideas how to fix it and show the correct number "123.45"?

well, looks like it is a better solution to use NSFormatter.numberStyle = .currency for this use-case — Artiom, Mar 03 '22 at 20:06

score 1 · Answer 1 · answered Mar 03 '22 at 20:22

1

The locale used for the input string must match the format of the string, so if it is a German format then use a German locale

let locale = Locale(identifier: "de_DE")
let string = Decimal(string: "123,4567", locale: locale)?
    .formatted(.number.precision(.fractionLength(precision)))

This uses Locale.current (Swedish in this example) for the output

123,46

Since this is a price here is a currency example

let string = Decimal(string: "123,4567", locale: .current)?
    .formatted(.currency(code: "EUR")
        .precision(.fractionLength(2))
        .rounded(rule: .down)
        .locale(.current))

€123,45

answered Mar 03 '22 at 20:22

Joakim Danielson

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Thanks, I see. So first of all I need to get a proper string-price to be able to format it to a Local I need? If it is "123,4567" I basically can not format it to $ US format 1,123.45? – Artiom Mar 03 '22 at 20:36
@ArtiomLemiasheuski Yes you can (although your example doesn't match). You do it in two steps as I have shown in the answer. See the last example where I use a locale for the output, change from `.current` to the one you want. I used `.current` in the example because that is the locale the user has selected – Joakim Danielson Mar 03 '22 at 20:43
I also noticed that prices such as 0.2460 are represented as 0,0000. Do you have an idea how to fix it? Is NSNumberFormatter is a better way to work with the prices? – Artiom Mar 03 '22 at 20:48
My problem general problem is that I have to use the regional location of the device for formatting. I am getting the price as a string in the format "1298,99" and need to represent it in Germany to 1.298,99 € and in the USA to $1,298.99. So I can not hard code any value. – Artiom Mar 03 '22 at 20:52
Thanks for your help. I just need to use locale.currencyCode :) – Artiom Mar 03 '22 at 22:17
1

Ok, maybe I misunderstood you a little then. I thought the original string was always a specific currency but it is the users currency. – Joakim Danielson Mar 04 '22 at 06:32

Leo Dabus · Accepted Answer · 2022-03-03T22:05:34.863

1

If all you need is to format your decimal number to be displayed using a specific currency what you need is Decimal.FormatStyle.Currency. It will automatically discard the excess of precision length:

let valueString = "1234,5678"
let decimalLocale: Locale = .init(identifier: "de_DE")
let currencyLocale: Locale = .init(identifier: "en_US")  // or current (used US locale just for demonstration purposes)
if let decimal = Decimal(string: valueString, locale: decimalLocale),
    let currencyCode = currencyLocale.currencyCode {
    let currencyStyle: Decimal.FormatStyle.Currency = .init(code: currencyCode, locale: currencyLocale)
    let currencyFormatted = decimal.formatted(
        currencyStyle.rounded(rule: .towardZero)
    )
    print(currencyFormatted)  // "$1,234.56\n"
}

edit/update:

I usually don't like manipulating strings but if your source doesn't have a specific format where sometimes de decimal separator is a comma and sometimes a period you need to replace your string comma with a period before converting it to Decimal:

let valueString = "1234,5678"
let currencyLocale: Locale = .init(identifier: "en_US")  // or current (used US locale just for demonstration purposes)
if let decimal = Decimal(string: valueString.replacingOccurrences(of: ",", with: ".")),
    let currencyCode = currencyLocale.currencyCode {
    let currencyStyle: Decimal.FormatStyle.Currency = .init(code: currencyCode, locale: currencyLocale)
    let currencyFormatted = decimal.formatted(
        currencyStyle.rounded(rule: .towardZero)
    )
    print(currencyFormatted)  // "$1,234.56\n"
}

edited Mar 03 '22 at 22:05

answered Mar 03 '22 at 21:29

Leo Dabus

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Thank you! It is almost what I need. The one problem is if the number is separated by a dot, instead of a comma ("1234,5678") the result in my case for en_US is $1,234.00. And same for en_DE, if it is separated by a dot("1234.5678") -> 1.234,00 € – Artiom Mar 03 '22 at 21:50
Can you show where is your value coming from? Is it coming from a text field? Check this post [How to input currency format on a text field (from right to left) using Swift?](https://stackoverflow.com/a/29783546/2303865) – Leo Dabus Mar 03 '22 at 21:52
sure, it is coming from a json file -> "avg_price": "0.0055" – Artiom Mar 03 '22 at 21:54
ok so you have no control over its format? Does your json contain the locale information? – Leo Dabus Mar 03 '22 at 21:54
unfortunately not :( – Artiom Mar 03 '22 at 21:55
and also no locale information in the json file. Only the price in a format of "123.45" – Artiom Mar 03 '22 at 22:02
@ArtiomLemiasheuski check my last edit – Leo Dabus Mar 03 '22 at 22:05

Swift show price depends on Locale

2 Answers2