The main service I am aware of is dididache or 嘀嘀打车 in Chinese which was apparently launched in 2012 (same as Uber).
My observation is that a lot of people just call their preferred driver, too. In the event that the driver is busy, they generally forward the business to a trusted friend. It's pretty hard to compete with free, personally reputation-audited referrals and 24 hour service.
Further, only certain cities have functional traffic: Chengdu being a prime example. Many Chinese cities' road networks have been so oversubscribed by the millions of new cars that have appeared in the last half decade or so that calling someone to pick you up is a physically impossible model during large portions of the day.
Yet another source of competition are e-bike or e-trike taxis, which have a few hundred dollar entry cost, hang around on many city corners, are totally unregulated and generally faster and cheaper (5-15元 = $1-3) than regular taxis (due to lack of road space).
I am skeptical Uber can generate any profits whatsoever in this market.