A couple years ago, maybe around Swift's debut, Apple began to mark all their sample code, projects, programming guides, technical notes, etc, as deprecated and unmaintained with a header on each page stating so, and putting it all in their "Documentation Archive" [0]
They've had a new push to make sure that the remaining official documentation is available in either Swift or Objective-C, but I have yet to see any attempt at migrating some of their best documentation: CoreBluetooth Programming Guide, CoreImage Programming Guide, or CoreData Programming Guide [1]. These are hugely helpful documents that take a much higher level approach than just API documentation and get to the heart of the design of a framework, with helpful diagrams, etc.
I understand that Apple has a huge body of work regarding documentation, and that it would be unfair for us to require them to never deprecate any of their documentation, but at this point, we basically have header files, documents automatically generated by header files, with several large swatch of that even being undocumented [2].
I do think that Apple made a huge effort with SwiftUI to provide meaningful, helpful documentation at the time of the announcement [3], and I don't want that to get lost in the discussion. Unfortunately the framework has iterated so quickly that much of it is out of date.
However, when Xamarin [4] independently documents some of Apple's APIs better than Apple does... it is indeed time for a call to action.
This is especially sad because Apple used to have some of the best documentation ever available. I basically learned how to program through using their documentation.
[0] - https://developer.apple.com/library/archive/navigation/
[1] - https://developer.apple.com/library/archive/documentation/Co...
[2] - https://nooverviewavailable.com
[3] - https://developer.apple.com/documentation/swiftui
[4] - https://twitter.com/akashivskyy/status/1187790245804367873