CRS-IUA is dependent on Commerce Reference Store and CRS-M. The server module is at CommerceReferenceStore/Store/Mobile/REST. The iOS source code is available in a separate distribution you can find on the Oracle Technology Network at:

http://www.oracle.com/technetwork/indexes/downloads/index.html.

The Configuration and Installation Manager section refers to the existing ATG Installation and Configuration Guide to guide you through the setup and configuration of the server with which the iPhone client interacts.