I've got a PHFetchResult containing the user's iCloud Shared Albums, however I can't find a way to determine whether a photo has been liked by one of the people it is shared with.
I've checked the metadata of the PHAssets that are returned, but the only vaguely related property is favourite, but that only records whether the user has hit the heart button in their own Photos app, not the likes from people who the asset has been shared with.
It looks like this data isn't available - the fact that I can't find anything in the docs suggests this - but I want to ask in case StackOverflow knows better!
I just spent about ten minutes combing the documentation, and running Google searches like this, and couldn't find any way to do this. I would expect this to be fairly easy to find if it existed. I'm 99.9% sure that if this existed I would have found it.
I'd really like to be proven wrong!