China is the second largest iOS app market in the world in terms of number of downloads, trailing only the US.

The willingness of Chinese customers to pay for their apps is still developing. We think that the growth in paid apps and in-app purchases on the China App Store will take the industry by surprise and that China will become a key market for developers and publishers.

As China grows in importance, iOS developers and publishers targeting Chinese customers will have to come to terms with marketing their apps in a new environment.

For example, we recently looked closer at a Chinese phenomena we call ‘ghost-downloaders’; companies that offer iOS app downloading and review-writing services to app publishers willing to violate Apple’s policies in order to reach high-ranking positions in the App Store rankings.

So, how much does it cost to reach the number one position on the China App Store for a day? During January 2012 it would have cost around RMB37,000 (or about USD5,870) and would have taken over 50,000 downloads.

The practice presents a problem to App Store customers who rely on number of downloads and rankings to make downloading/purchasing decisions. It also presents a problem for iOS publishers who abide by Apple’s policies, since ‘ghost-downloading’ intensifies competition for the coveted top rankings immediately following an app release. We will see how Apple deals with this problem.