IDK what time period you're talking about, but I thought around 10 years ago it was pretty good. You could download and install all the documentation locally,

IDK what time period you're talking about, but I thought around 10 years ago it was pretty good. You could download and install all the documentation locally, they had pretty thorough class documentation and also higher-level conceptual documents around various topics (seems like those are all deprecated now). Was able to basically just code against the standard library and the documentation actually seemed to be one of the perks of native development, since it was all in a standard place/format with pretty good baseline quality. I'm working with a greater variety of library dependencies now and of course the documentation isn't as consistent. It's kind of mind-boggling how Apple seems to have gotten bad at this now.