I would like to hear an Apple attorney confirm this theory and explain whether this was Apple's intention.
I always wondered why Apple thought a new language was required, not that Swift isn't interesting but still, it is odd that they introduced it and didn't mention that they patented it.
Also, the patents cover more than just optional chaining. There are two:
9,952,841 issued in 2018
9,329,844 issued in 2016
Presumably there are more that are pending.
By the way here is a list of Apple patents pending, the public ones anyway.
I see there an attempt to patent an API, and if I recall, the issue of copyrighting APIs came up in the Java lawsuit between Oracle and Google.