In a project I was working on I noticed that we kept repeating the code to do the string formatting for the localization file. This meant you could not just use the value, you first needed to check what parameters were required. One way to avoid this problem is to use Swift enums. This method is also useful for unit testing your localizations.
Assume you have the following 3 localizations in your strings file:
"TestNoParams" = "This is a test message";
"TestOneParam" = "Hello %@";
"TestTwoParams" = "This is a test with %d Pictures and %d Users";
Now you can use the following enum, protocol and extension to reference your strings:
protocol LocalizationProtocol {
var key: String { get }
var value: String { get }
}
extension LocalizationProtocol {
private func localizationValue() -> String {
return NSLocalizedString(key, comment:key)
}
private func localizationValueWithFormat(parameters: CVarArgType...) -> String {
return String(format: localizationValue(), arguments: parameters)
}
}
enum Localizations: LocalizationProtocol {
case TestNoParams
case TestOneParam(name: String)
case TestPicturesAndUsers(pictures: Int, users: Int)
var key: String {
switch self {
case .TestNoParams: return "TestNoParams"
case .TestOneParam: return "TestOneParam"
case .TestPicturesAndUsers: return "TestTwoParams"
}
}
var value: String {
switch self {
case .TestOneParam(let name):
return localizationValueWithFormat(name)
case .TestPicturesAndUsers(let pictures, let users):
return localizationValueWithFormat(pictures, users)
default:
return localizationValue()
}
}
}
Now to use it you just need to call the enums value method:
let testNoParam = Localizations.TestNoParams.value
let testOneParam = Localizations.TestOneParam(name: "users name").value
let testTwoParams = Localizations.TestPicturesAndUsers(pictures: 4, users: 500).value
The example I have shown is simplified, but you can also nest enums to provide a nice grouping for your localizations. For instance you could have your enums nested by ViewController. This is an example for a welcome message: Localizations.Main.WelcomeMessage.value