Foundation ICU

This version of the ICU4C project contains customized extensions for use by the Foundation package. It is automatically extracted from Apple OSS Distribution’s ICU to add Swift Package Manager support. Improvements to ICU’s core functionality should be proposed to the upstream ICU4C library and not to this package.

• Sources: https://github.com/apple/swift-foundation-icu
• API Docs: https://unicode-org.github.io/icu/userguide/icu4c/

Versioning

FoundationICU follows the same version number as the upstream ICU4C project that it contains. The oldest version that this package supports is ICU 70.1.

Adding FoundationICU as a Dependency

This package is intended to be a dependency for the Foundation package. It is not useful as a “general purpose” ICU4C library because all files irrelevant to the SwiftPM build are removed. The package is considered a private implementation detail of Foundation, and its API surface and structure is likely to change between major versions.

To use the FoundationICU library in a SwiftPM project, add the following lines to the dependencies in your Package.swift file:

.package(url: "https://github.com/apple/swift-foundation-icu", from: "70.1"),

Include "FoundationICU" as a dependency for your target:

.target(name: "<target>", dependencies: [
    .product(name: "FoundationICU", package: "swift-foundation-icu"),
]),

Finally, add import FoundationICU to your source code. You should now be able to directly use/extend ICU types:

import FoundationICU

extension UCalendarAttribute {
    static let lenient = UCAL_LENIENT
    static let firstDayOfWeek = UCAL_FIRST_DAY_OF_WEEK
    static let minimalDaysInFirstWeek = UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
}

Future Improvements

• Data file handling: currently, a pre-built data file is checked in as a binary file. In the future, we would like to check in the source files instead and build the data as a shared library to avoid the need to maintain and load a separate data file.