Why does NumberFormatter.Style.currency return "XXX"?

Using Swift
,
1

Unfortunately, .currency and .currencyISOCode return "XXX" instead of an actual currency symbol or code (see NumberFormatter.Style in the Apple Developer documentation). Do you have an idea, why this occurs? Note that I changed the formatter locale from "en" (which is returned by Locale.current) to "de", but that still returns "XXX".

import SwiftUI
import Foundation

struct ExpenseRow: View {
    
    var body: some View {
        Text(amountAsCurrency())
    }

    fileprivate func amountAsCurrency() -> String {
        let str = "\(format: 35.6689, using: .currency)"
        print(str)
        return str
    }
}

// https://www.hackingwithswift.com/articles/178/super-powered-string-interpolation-in-swift-5-0
extension String.StringInterpolation {
    mutating func appendInterpolation(format value: Float, using style: NumberFormatter.Style) {
        let formatter = NumberFormatter()
        //print("formatter.locale = \(formatter.locale!)")
        //print("Locale.current = \(Locale.current)")
        
        formatter.locale = Locale(identifier: "de")
        formatter.numberStyle = style

        if let result = formatter.string(from: value as NSNumber) {
            appendLiteral(result)
        }
    }
}
2

Is this really SwiftUI related, or “just” a problem with NumberFormatter?

What happens if you specify the locale as "de_DE", i.e. with language and region?

1 Like
3

I've edited the following as you suggested and that lets the currency style show the currency symbol. Thanks @Martin
formatter.locale = Locale(identifier: "de_DE")

When I remove that line entirely, thinking that this should return something like $173.04, because formatter.locale defaults to "en", I get this (with actual mock data):

58

:thinking:

Is there an Xcode setting for the locale? The macOS region and language on the iMac I'm on is actually Germany/German.

4

It seems that this a problem about NumberFormatter (which is part of the Foundation framework) and not a problem about the Swift language. The Apple Developer Forum: Cocoa may be a better place to get help.

5

I just learned that the GPS position of the Simulator for Xcode is "US" by default and that is why

print("formatter.locale = \(formatter.locale!)")
print("Locale.current = \(Locale.current)")

return "en (current)".

On an actual iOS device, that should be "en_DE (current)"