They're newer, but they aren't at all similar to what ships on Apple's OSes anymore. These days, the layers have flipped, and CoreFoundation is becoming a wrapper around swift-foundation.

CF functions toll-free bridge the CF types to their Foundation counterparts and invoke the corresponding Objective-C API, which is either implemented directly in Swift, or is a wrapper around the Swift function.

An Apple employee on the Foundation team posted an example of how calling `CFCalendarCreateWithIdentifier` works here: https://forums.swift.org/t/swift-foundation-now-available/73...

I'm sure it's still a work-in-progress, but their definitive goal is for the OSS swift-foundation codebase to be the same as what ships in their OSes, which was never the case with swift-corelibs-foundation.

Edit: I found a conference talk by some Apple folks that goes into more detail https://www.youtube.com/watch?v=wn6C_XEv1Mo

swift-foundation will never be the code that ships on the OS, mostly because they always have some private bits they won't expose. Come back when URL bookmarks are part of the open source dump.

Of course the entire binary will never be the same, but the implementation of (for example) DateComponents.swift in OSS swift-foundation will be the same implementation that is used to build the OS library.

Going forward, the bedrock of both the OSS package and the platform [Core]Foundation.framework will be swift-foundation. This is distinct from SCF, which was a novel Swift wrapper around CoreFoundation.

The code in CoreFoundation.framework was basically built out of that repo, though.

Sure, but that’s not relevant in the timeline of the OP.