The site of Google Custom Search Objective-C library offers a library and a framework to access the JSON APIs. It aims to be flexible to work with Google APIs for iOS and Mac OS X apps. It is compatible with iOS3+ and Mac OS X 10.5+. Available example applications, support, and contributions.
Service discovery is not an easy task in today's Web. Discovering an API requires searching through a large number of services on the Internet and then reading pages of documentation to figure out how to use the ones that may match your application. This is the case in Programmable Web as well. The API directory shows over 5000 APIs which are manually categorized in over 50 service categories.