Borrowing wholesale @Deskana's ticket description from T191333:

There's now a magic word which allows editors on the English Wikipedia to override the descriptions from Wikidata, per T184000. The previous method of accessing the descriptions using prop=pageterms now needs to be replaced with prop=description. The output from the new method is quite different, so there'll be a few changes that need to be made.

Old method: https://en.wikipedia.org/w/api.php?action=query&titles=Wagon%20Train&prop=pageterms

New method: https://en.wikipedia.org/w/api.php?action=query&titles=Wagon%20Train&prop=description

For iOS this means everywhere we have "prop" using "pageterms" we'll want to change to "description". I think we'll then no longer need the "wbptterms" "description" param. We'll just have to then extract the description straight from the "description" rather than from it's previous "terms" "description" array.