OCMockSampleAppIOS shows how to use OCMock to test an iOS application.
To get the code:
git clone https://github.com/acani/OCMockSampleAppIOS.git
cd OCMockSampleAppIOS
git submodule update --init
open OCMockSampleAppIOS.xcodeproj
OCMockSampleAppIOS requires Xcode 4.2 or later to run because it uses ARC.