[ASRangeController] Fix Major Range Mode Updating Issues

[Adlai-Holler]

This morning Michael and I found that our range mode updating is basically not working at all for a couple reasons.

• ASCollectionNode and ASTableNode declare their conformance in a category, which apparently doesn't work and causes the runtime to return NO for conformsToProtocol:
• Pinterest (and I'm sure other apps) have ASViewControllers with non-table, non-collection nodes. Sometimes these are plain old ASDisplayNodes. None of them conform to the update protocol.
• ASTableNode and ASCollectionNode did not implement +setRangeModeForMemoryWarnings: so they actually didn't conform to the updating protocol. This also means none of our users is calling that method or it would have crashed.
• Worst of all, we had no idea that none of this was working.

So

• Move the conformances in ASTableNode/ASCollectionNode to the main @interface instead of the category. This makes them return YES from conformsToProtocol.
• Allow ASViewController to conform to the range updating protocol as well as its node.
• Add a one-time-per-VC log if we try to adjust the range mode but can't because neither the VC nor the node conforms to the protocol.
• BREAKING Remove +setRangeModeForMemoryWarnings from the protocol and replace with a global method +[ASDisplayNode setRangeModeForMemoryWarnings:].
  • I think we can land this even with the breaking change.
  • Obviously nobody was calling it or they would have gotten crashes.
  • It's not clear what calling it on, say, ASTableNode would have done. It would probably have called through to ASRangeController, which would have affected ASCollectionNode as well.
  • It would be a pain to override for every conforming node/VC.

@appleguy @maicki @levi This is pretty urgent. I think we should cherry-pick this to 6.7 if it's approved.

[levi]

👍

[maicki]

LGTM