SmallStrings | Reduce localized .strings file sizes by 80%

Maintained by Emerge Tools

🧪 Note: This repo is meant as a proof-of-concept on how to reduce localization size. Adjustments may be needed for your specific project.

How does it work

• Convert .strings files (of the form App.app/*.lproj/Localizable.strings only) into a minified form
• Eliminate key duplication (read more about the strategy), this typically reduces the size by about 50%
• Keep small files in a compressed form on disk, using LZFSE, to reduce the size further
• Replace the original language.lproj/Localizable.strings with placeholders that have one key-value pair each. This shows Apple that the same languages are still supported, so that it can pick the correct one based on the user's settings.
• Use the iOS library that replaces NSLocalizedString with a new version, SSTStringForKey that fetches values for keys from this minified format.

Usage

Cocoapods

Add this to your Podfile:

pod 'SmallStrings'

Then add a Run Script build phase after the "Copy bundle resources" phase:

cd ${PODS_ROOT}/SmallStrings && ./localize.sh ${CODESIGNING_FOLDER_PATH} ${DERIVED_FILES_DIR}/SmallStrings.cache

Lastly, replace all usages of NSLocalizedString(key, comment) with SSTStringForKey(key).

Manual

• Add Source/SSTSmallStrings.{h,m} to your project.
• Create a compress binary via clang -O3 compress.m -framework Foundation -lcompression -o compress and put the executable in the same directory as localize.{rb,sh}.
• Add a build step with cd /path/to/SmallStrings && ./localize.sh ${CODESIGNING_FOLDER_PATH} ${DERIVED_FILES_DIR}/SmallStrings.cache.
• Lastly, replace all usages of NSLocalizedString(key, comment) with SSTStringForKey(key).