We have lined iOS localization in a number of tutorials, together with one which exhibits the best way to totally localize an app utilizing String Catalogs. Nonetheless, these tutorials depend on the system language to find out the app’s language. However what if you wish to give customers the flexibility to decide on their most well-liked language, whatever the system setting? And what in order for you the language to replace immediately—with out restarting the app? That’s precisely what this tutorial will educate you.
Earlier than we get began, I like to recommend reviewing the sooner iOS localization tutorial should you’re not conversant in String Catalogs. The demo app used on this tutorial builds on the one from that information.
The Demo App
We’re reusing the demo app from our iOS localization tutorial—a easy app with primary UI components for instance localization ideas. On this tutorial, we’ll lengthen it by including a Settings display that lets customers choose their most well-liked language. The app will then replace the language immediately, without having to restart.
Including App Languages and App Settings
Earlier than we begin constructing the Setting display, let’s first add an AppLanguage enum and an AppSetting class to the challenge. The AppLanguage enum defines the set of languages that your app helps. Right here is the code:
enum AppLanguage: String, CaseIterable, Identifiable {
case en, fr, jp, ko, zhHans = "zh-Hans", zhHant = "zh-Hant"
var id: String { rawValue }
var displayName: String {
swap self {
case .en: return "English"
case .fr: return "French"
case .jp: return "Japanese"
case .ko: return "Korean"
case .zhHans: return "Simplified Chinese language"
case .zhHant: return "Conventional Chinese language"
}
}
}
Every case within the enum corresponds to a selected language, utilizing customary locale identifiers as uncooked values. For instance, .en maps to "en" for English, .fr to "fr" for French, and so forth. The displayName computed property gives a user-friendly label for every language. As an alternative of displaying uncooked locale codes like “en” or “zh-Hans” within the UI, this property returns readable names corresponding to “English” or “Simplified Chinese language.”
The AppSetting class, which conforms to the ObservableObject protocol, is a straightforward observable mannequin that shops the person’s chosen language. Right here is the code:
class AppSetting: ObservableObject {
@Revealed var language: AppLanguage = .en
}
By default, the language is ready to English. Later, when the person selects a distinct language from the Settings display, updating this property will trigger SwiftUI views that depend on the app’s locale to re-render utilizing the brand new language.
Constructing the Setting Display screen
Subsequent, let’s construct the Settings display. It’s a easy interface that shows an inventory of all of the supported languages. Under is the code for implementing the setting view:
struct SettingView: View {
@Setting(.dismiss) var dismiss
@EnvironmentObject var appSetting: AppSetting
@State non-public var selectedLanguage: AppLanguage = .en
var physique: some View {
NavigationStack {
Kind {
Part(header: Textual content("Language")) {
ForEach(AppLanguage.allCases) { lang in
HStack {
Textual content(lang.displayName)
Spacer()
if lang == selectedLanguage {
Picture(systemName: "checkmark")
.foregroundColor(.main)
}
}
.onTapGesture {
selectedLanguage = lang
}
}
}
}
.toolbar {
ToolbarItem(placement: .topBarTrailing) {
Button("Save") {
appSetting.language = selectedLanguage
dismiss()
}
}
ToolbarItem(placement: .topBarLeading) {
Button("Cancel") {
dismiss()
}
}
}
.navigationTitle("Settings")
.navigationBarTitleDisplayMode(.inline)
}
.onAppear {
selectedLanguage = appSetting.language
}
}
}
#Preview {
SettingView()
.environmentObject(AppSetting())
}
The view merely lists the obtainable languages as outlined in AppLanguage. The presently chosen language exhibits a checkmark subsequent to it. When the person faucets “Save,” the chosen language is saved to the shared AppSetting object, and the view is dismissed.
In the principle view, we add a Setting button and use the .sheet modifier to show the Setting view.
struct ContentView: View {
@EnvironmentObject var appSetting: AppSetting
@State non-public var showSetting: Bool = false
var physique: some View {
VStack {
HStack {
Spacer()
Button {
showSetting.toggle()
} label: {
Picture(systemName: "gear")
.font(.system(dimension: 30))
.tint(.main)
}
}
Textual content("ProLingo")
.font(.system(dimension: 75, weight: .black, design: .rounded))
Textual content("Study programming languages by engaged on actual tasks")
.font(.headline)
.padding(.horizontal)
.
.
.
.
.
.
}
.padding()
.sheet(isPresented: $showSetting) {
SettingView()
.environmentObject(appSetting)
}
}
}
Enabling Actual-Time Language Adjustments
At this level, tapping the gear button will deliver up the Settings view. Nonetheless, the app would not replace its language when the person selects their most well-liked language. To implement dynamic language switching, we’ve to connect the .atmosphere modifier to ContentView and replace the locale to match the person’s choice like this:
VStack {
...
}
.atmosphere(.locale, Locale(identifier: appSetting.language.id))
This line of code injects a customized Locale into the SwiftUI atmosphere. The .locale key controls which language and area SwiftUI makes use of for localizable views like Textual content. The locale is ready to match the language the person chosen in settings.
The app can now replace its language on the fly. For instance, open the Settings view and choose Conventional Chinese language. After saving your choice and returning to the principle view, you may see the UI immediately up to date to show all textual content in Conventional Chinese language.
Utilizing LocalizedStringKey
It’s possible you’ll discover a bug within the app. After altering the language to Conventional Chinese language (or different languages) and reopening the Settings view, the language names nonetheless show in English.
Let’s check out the code that handles the show of language title:
Textual content(lang.displayName)
It’s possible you’ll surprise why the Textual content view doesn’t deal with the localization robotically. On this case, SwiftUI treats lang.displayName as a plain textual content, which suggests no automated localization occurs, even when the string matches a key within the String Catalog file. To make the localization work, you must convert the String to a LocalizedStringKey like this:
Textual content(LocalizedStringKey(lang.displayName))
Utilizing LocalizedStringKey triggers the localization lookup course of. Once you run the app once more, you may see the language names within the Settings view displayed in your chosen language.
Abstract
On this tutorial, you discovered the best way to implement in-app language switching in iOS utilizing SwiftUI, permitting customers to alter languages with out restarting the app. We explored the best way to create a Settings display for language choice, enabled real-time localization updates, and discovered the significance of utilizing LocalizedStringKey for correct string localization.
The code and ideas offered right here present a basis for implementing language switching in your individual iOS apps. Be at liberty to adapt this method on your personal iOS apps that require multi-language help.
