CRS-IUA is dependent on Commerce Reference Store and CRS-M. The server module is at CommerceReferenceStore/Store/Mobile/REST. The iOS client consists of several Xcode projects and is a separate download from the Oracle Technology Network (OTN):

http://www.oracle.com/technetwork/apps-tech/atg-web-commerce-1740796.html

The CIM Configuration 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.