Localize iOS Apps with AI

What is iOS localization?

iOS localization is making your iOS app available to multilingual audiences and adapting it to cultural and topical nuances. 

Localization in Xcode is specifically about setting up resources for each language you support. 

The iOS app localization process involves three main steps:

1. Preparing, or Internationalizing (often abbreviated i18n), your iOS app
2. Translating user-facing texts
3. Importing translations and testing

iOS internationalization is an essential part of localization, because it allows your iOS app to support multilingual content.

Internationalizing Your iOS App

iOS internationalization is adapting your code to ensure strings are translated and formatted correctly. This helps you avoid redesigning layouts or rewriting code later. 

Thankfully, with string catalogs, the process is much easier than it used to be.

Step 1: Making Text Localizable

In legacy workflows, you needed to wrap your app’s strings in a way that Xcode and translation tools understood.

But with SwiftUI, you don’t need to do anything: any hard-coded string you place in a SwiftUI Text, Label, Button, etc., is automatically localizable.

You only need to manually make text localizable when:

• You have text outside of SwiftUI, like error messages, ViewModel Text, Login validation strings. In these cases, use String(localized:). 

• You’re targeting devices with older versions that don’t support current localization APIs, like iOS 16 or earlier. In this case, wrap all user-facing text in NSLocalizedString().

Step 2: Adding comments for context

Comments are useful when translating strings with both manual and automatic methods. Use comment: within your Text ().

Text("Select an item", comment: “The label of a drop down menu to allow users to navigate.”)

Step 3: Creating a String Catalog

Now, let’s add a string catalog to your iOS project.

1. Right-click on your project and select New File from Template.

2. Search for String Catalog and add it. The default name will be Localizable.xcstrings. No need to change it.

3. Populate your string catalog with your text. Go to Product → Build. Xcode takes care of the rest. You can review the text later by clicking on your .xcstrings file and then go to Editor → Assistant from the menu.

Step 4: Add variants by plural or by device

Some strings need different versions depending on context, such as plural forms in different languages or text that changes by device. These variations help ensure your text feels natural and appropriate across languages, devices, and contexts. 

You can manage both in the String Catalog. 

Pluralization

For plurals, start by localizing a string that depends on a numeric value, such as:

Text("\(count) items")

Go to the string catalog and right-click in the key view. Choose Vary by Plural. Xcode automatically adds all required plural categories for that language. Fill in the text for each plural form, and the system will pick the right one at runtime.

Here’s an example .xcstrings file with plural variations:

{
  "version": "1.0",
  "sourceLanguage": "en",
  "strings": {
    "items_count": {
      "comment": "Number of items - English only supports 'one' and 'other'",
      "extractionState": "manual",
      "localizations": {
        "en": {
          "variations": {
            "plural": {
              "one": {
                "stringUnit": {
                  "state": "translated",
                  "value": "%lld item"
                }
              },
              "other": {
                "stringUnit": {
                  "state": "translated",
                  "value": "%lld items"
                }
              }
            }
          }
        }
      }
    },
    "messages_count": {
      "comment": "Number of messages",
      "extractionState": "manual",
      "localizations": {
        "en": {
          "variations": {
            "plural": {
              "one": {
                "stringUnit": {
                  "state": "translated",
                  "value": "You have %lld new message"
                }
              },
              "other": {
                "stringUnit": {
                  "state": "translated",
                  "value": "You have %lld new messages"
                }
              }
            }
          }
        }
      }
    }
  }
}

{
  "version": "1.0",
  "sourceLanguage": "en",
  "strings": {
    "items_count": {
      "comment": "Number of items - English only supports 'one' and 'other'",
      "extractionState": "manual",
      "localizations": {
        "en": {
          "variations": {
            "plural": {
              "one": {
                "stringUnit": {
                  "state": "translated",
                  "value": "%lld item"
                }
              },
              "other": {
                "stringUnit": {
                  "state": "translated",
                  "value": "%lld items"
                }
              }
            }
          }
        }
      }
    },
    "messages_count": {
      "comment": "Number of messages",
      "extractionState": "manual",
      "localizations": {
        "en": {
          "variations": {
            "plural": {
              "one": {
                "stringUnit": {
                  "state": "translated",
                  "value": "You have %lld new message"
                }
              },
              "other": {
                "stringUnit": {
                  "state": "translated",
                  "value": "You have %lld new messages"
                }
              }
            }
          }
        }
      }
    }
  }
}

Device variations

For device-specific text — like “Tap” on iOS versus “Click” on macOS — Control-click the same key and choose Vary by Device.

Add the devices you want to customize and enter the appropriate message for each. When the app runs, it displays the version that matches the current device.

Step 5: Add Languages

Here’s an easy way to add (and remove) languages:

1. Select your project file and then see the Info tab on the right-hand panel. 
2. Under the Localizations section, click on the plus (+) sign at the bottom left.
3. Add languages you want to display your iOS app in.

All language files and translations will be added to the same .xcstrings file.

(Optional) Step 6: Export your xcstrings File

Though an API or Git integration with a software localization tool is the fastest way to get translations, you may want to send files manually. In this case, just grab the .xcstrings file from your iOS folder.

When you re-upload it after PTC is done translating, PTC will replace the original.