Third-party travel apps/platforms seem to completely outclass official apps of the airlines in China, to a point that users there generally don't have to be bothered with the official apps. I personally haven't used them, but I've seen my Chinese friends use mostly those third-party super-apps for all sorts of things related to travel (including seat selection). Between umetrip (航旅纵横) and TravelSky, they don't seem to need to ever use official apps of the airlines.