OCMockito is an Objective-C mocking library modeled after Mockito for Java. It provides mock objects, stubbing, and verification for unit tests. The library is built as a framework or static library, targeting iOS, macOS, tvOS, watchOS, and visionOS. Its architecture is modular: Core (public API), Mocking (NSProxy-based mock classes), Stubbing (invocation containers and answer objects), Verifying (invocation checkers and verification modes), Invocation (invocation matcher, call stack analysis, printing), and Helpers (chain-of-responsibility for argument getters and return value setters). The primary entry point is the OCMockito.h header, which exposes macros like mock(), given(), verify(), etc. Dependencies include OCHamcrest for matchers and failure reporting, and XCTest for test integration. The codebase demonstrates solid software engineering with extensive unit tests (XCTest), though there are minor maintenance concerns such as duplicated public headers, hardcoded paths in examples, and reliance on global singleton swizzling state that may cause cross-test contamination. Overall, it is a well-maintained and widely used testing library.