An incomplete list here but most aren’t a license that compels them to contribute anything.

https://opensource.apple.com/projects/

I think it's fair to say Apple's cross platform work is a couple of Android and PC apps, the Mac boot loader, and Swift. Even on this page, Apple seems more like a user of the community projects than a contributor and the Apple projects seem to be for internal use or for Apple platforms. Kind of misses the point in being cross platform the way librepod is aiming to be.

	▲	dagmx 44 minutes ago \| parent [-]
		That’s not what this particular thread is about, you’re referencing the parent topic but not the current thread. This is about whether they contribute to open source or not.