Categories

This category adds diffing comparisons similar to adding the object into an NSSet, where the object’s isEqual: method drives the uniqueness of the object.

For instance, an NSString’s isEqual: will compare the value of the strings. So if you were to diff @cat and @cat each object would have the same diff identifier.

However objects that don’t implement a custom isEqual: (e.g. the NSObject base class), the diff will default to simple pointer comparisons to establish uniqueness.