# Extra Clang Tools 21.1.6 documentation

## clang-tidy - objc-missing-hash

# objc-missing-hash

Finds Objective-C implementations that implement `-isEqual:` without also appropriately implementing `-hash`.

Apple documentation highlights that objects that are equal must have the same hash value: https://developer.apple.com/documentation/objectivec/1418956-nsobject/1418795-isequal?language=objc

Note that the check only verifies the presence of `-hash` in scenarios where its omission could result in unexpected behavior. The verification of the implementation of `-hash` is the responsibility of the developer, e.g., through the addition of unit tests to verify the implementation.