String.localizedStringWithFormat returns wrong result

Question

I'm trying to localize string which contains range like 1..2. I'm using String.localizedStringWithFormat:

func testLocalizableString() -> String {
    let lowerBound = 1
    let upperBound = 2
    return String.localizedStringWithFormat(
        NSLocalizedString("Unit.Meters.Range", value:"%d-%dm", comment: ""),
        [lowerBound, upperBound]
    )
}

However, I get strange result: "103,413,600-0m".

If I use only one argument (just "%dm", not "%d-%dm") and pass only one number everything is fine.

What could be wrong with my code and how to properly format localizable string with CVarArg argument?

Answer 1

The second parameter in

String.localizedStringWithFormat(_ format: String, _ arguments: CVarArg...)

is a variadic parameter, which means that you must pass zero or more arguments of the specified type, not an array:

func testLocalizableString() -> String {
    let lowerBound = 1
    let upperBound = 2
    return String.localizedStringWithFormat(
        NSLocalizedString("Unit.Meters.Range", value:"%ld-%ldm", comment: ""),
        lowerBound, upperBound
    )
}

Note also that the format specifier for Int is %ld,not %d.