CUPS was done by Easy Software Products, in 1997. Apple adopted it only in 2002.
Swift is a language entirely in the control of Apple, mainly targeting Apples platforms. With little to no community engagement.
Bonjour is not really cross platform, and not really open source either as it has lots of strings attached to the license and terms one can use it under.
(I wouldn't say that Apple has done "nothing" -- but to credit them for doing much is also a stretch)
HLS -- created by Apple, just about everybody uses it for streaming on the web.
And I think CSS animations and transforms mostly came out of Apple; at any rate, they're very similar to the animations and transforms in UIKit that originally came from NeXT.
Apple being gung-ho to push a technology to further nail Flash to the cross whether the actual reason, at least is consistent with their MO and not some great contribution to open standards.
Cups - https://en.wikipedia.org/wiki/CUPS
Swift - https://en.wikipedia.org/wiki/Swift_(programming_language)
Zeroconf - https://en.wikipedia.org/wiki/Bonjour_(software)
I think they're bad, opaque opensource maintainers, but they did release some popular things that have communities on other systems.
I do wish they just contributed to nickel or something else though rather than doing their NIH as usual.