Optional is a Swift type that contains a value of any type. Obj-C doesn't have anything matching that behavior at all.
What's been done here is Obj-C has gained the ability to annotate any pointer valued type as either nullable or non-nullable. This does not affect the runtime behavior of the code in the slightest. It doesn't even affect the semantics of Obj-C. All it does for Obj-C is let the compiler yell at you if you pass nil to a non-nullable parameter / property.
The real point of these annotations is so Swift can be more intelligent when translating the obj-c API to Swift, choosing to use the correct optional type (or no optional type at all).
Not exactly. ObjC code cannot usefully benefit from those annotations (yet? more likely ever). At most, it's good for documenting your ObjC code for fellow readers. The actual use appears in the Swiftland where instead of implicitly unwrapped optionals you get proper explicit optionals or explicit non-optionals.
They've been doing it for a while in the Swift overlay module. I'm really happy that this is officially added to obj-c because it provides very valuable API documentation, even if it won't have much practical effect on the code.
I grew up reading SciFi in both Mandarin and English. In my impression, though not flawless, this series is the only long-form novel produced in China that can stand among the best SciFi literature in the west.
To those who want to try something else, here is an incomplete (personal) list of famous contemporary Chinese Sci-Fi novel authors:
Wang Jinkang (王晋康, quite productive), Chen Qiufan (陈楸帆, just started to publish books recent years), Han Song (韩松)
To my surprise, when I wrote this list, I suddenly realized how few names I could think of, even after I looked up in a Chinese website Douban ( http://book.douban.com/tag/%E4%B8%AD%E5%9B%BD%E7%A7%91%E5%B9... ). The truth is: there are quite a few good Sci-Fi writers with a whole bunch of brilliant Sci-Fi short stories in China, but few of them ever writes full-length novels, not to mention "good" or "famous" ones.
So you would say that the article is correct about the lack of science fiction authors in China? Are there any other Mandarin SF novels that you would recommend, even if they don't measure up to the level of "The Three-Body Problem"? I grew up reading exclusively western SF (Asimov, Clarke, Niven, Heinlein, Vinge, etc) and reading SF is still one of my favorite pastimes. I took some Mandarin language classes in College, and I'd like to try reading some Chinese SF.
Someone posting a link to a short story by one of the greatest SF writers all of time, whose writings spawned entire threads of reflexion and discussion in many disciplines; and a HN comment being a dismissive tl;dr.
I didn't find the comment to be dismissive actually. What's wrong with writing a story that explores the boundaries of science and god? That must have been a pretty natural thing for someone living in Asimov's era to do.