My current project has a single target and multiple schemes. Each scheme represents the same app for different countries/regions. It’s essentially the same application with minor adjustments made for each of the supported jurisdictions.

In Xcode projects, you define supported languages at the project level (not scheme level). Because of this structure, each app variant inherits the same language settings.

My task was to force each app variant to support only the language for the region it was released in. The French app should only support French, no matter what the user’s device language is set to, and so on. This decision was made because large portions of the app are web-based and only supported a single language.

Solution

There are multiple ways to solve this problem. What follows is the approach that worked best for my particular use case, given the project’s current structure:

First, create a build configuration file for each of the schemes and define the LOCALIZATIONS_TO_KEEP variable.

LOCALIZATIONS_TO_KEEP = fr

Then, add a new build phase called “Remove unused localizations.” Remember to position it after the “Copy Bundle Resources” build phase:

echo "Keeping only ${LOCALIZATIONS_TO_KEEP}.lproj"
echo "Application .app path: ${CODESIGNING_FOLDER_PATH}"

# Only search in the main app bundle, excluding 
# Frameworks directory and other dependency folders
find "${CODESIGNING_FOLDER_PATH}" -type d -name "*.lproj" \
  -not -path "*/Frameworks/*" \
  -not -path "*/PlugIns/*" \
  -not -path "*/Watch/*" \
  -not -path "*/SwiftPM/*" \
  | grep -v "${LOCALIZATIONS_TO_KEEP}.lproj" \
  | xargs rm -rf

CODESIGNING_FOLDER_PATH is an environment variable used in Xcode build scripts that represents the path to the app bundle being built. It typically points to the directory where the compiled application and its resources are placed before code signing occurs.

You’ll want to exclude locations where third-party dependencies might be located, because you can’t guarantee that they support the same language you want to force the app to use.

You can verify that the script works by navigating to ${CODESIGNING_FOLDER_PATH} in derived data and checking if the script successfully removed all other localization files.

Alternative Solutions

This issue could be solved by setting CFBundleLocalizations and CFBundleDevelopmentRegion IF my project used separate targets instead of separate schemes for different apps.

Alternatively, I could dynamically select Info.plist files for each of the schemes. I opted against this approach since the project already had build configurations defined for each of the schemes.