Localized strings and the order of parameters

Find out how to set the order of parameters per each language.

The Problem

Sometimes you want to be able to manipulate the order of parameters in a specific way when localizing strings.

For example, you might have a sentence in US English:

“Manager Tom had called Ana to come to the office.“

Its counterpart in some other language might use a different structure, so the need to put Ana before Tom comes as a must.

Let’s say for the sake and simplicity of this example that this sentence is in British English as:

“Ana got a call from manager Tom to come to the office.“

But how do you do this without getting your View code dirty? Let’s see…

How is it usually done?

People usually do not make use of the ordered arguments and end up with the following content in the localizable files:

US English
"invite_unordered" = "Manager %@ had called %@ to come to the office.";
UK English
"invite_unordered" = "%@ got a call from manager %@ to come to the office.";

And the code inevitably ends up looking something like this:

    let manager = "Tom"
    let hr = "Ana"
    let isUK = Locale.current.identifier == "en_GB"

    var body: some View {
        if self.isUK {
            Text(self.localize(key: "invite_unordered", arguments: self.hr, self.manager))
        } else {
            Text(self.localize(key: "invite_unordered", arguments: self.manager, self.hr))
        }
    }

    func localize(key: String, arguments: CVarArg...) -> String {
         String(format: NSLocalizedString(key, bundle: .main, comment: ""), arguments)
    }

Notice how you have to arrange the order of the properties self.hr and self.manager in order to accommodate the needs of a specific language. Needless to say, burdening the view or its view model with the localization logic is far from an optimal solution. It looks clumsy, even when we have just one additional language. You can just imagine what it would look like with twenty or more.

We can do better

Simply by making use of the ordered parameters, we can manipulate the order of the parameters exactly where it is needed. And that is on the level of the localization file for every specific language.

How?

We can do that easily by numerating every parameter, followed by a dollar sign.

%1$@ %2$@ %3$@ ....

So now our localization files look like this:

US English
"invite_ordered" = "Manager %1$@ had called %2$@ to come to the office.";
UK English
"invite_ordered" = "%2$@ got a call from her manager %1$@ to come to his office";

And our view is now free from specific case-by-case localization worries 🥳

struct ContentView: View {

    let manager = "Tom"
    let hr = "Ana"

    var body: some View {
        Text(self.localize(key: "invite_ordered", arguments: self.manager, self.hr))
    }
}

Summary

That is it! XCode and Swift make it really easy to set the positional specifiers for multiple parameters and manage their order. This can be useful for almost any project that demands localization.

Documentation

12072023.1