What are faulting and lazy loading in Core Data?
Essence
A fault is a placeholder: an NSManagedObject whose objectID and type are known but whose properties haven't been loaded from the store yet. A fetch returns faults (unless returnsObjectsAsFaults = false is set), and on the first attribute access the fault "fires": Core Data queries the store (or uses the coordinator's row cache) and populates the object. Relationships are faults too: to-one is a fault on an object, to-many a fault on a Set.
That is lazy loading in Core Data: memory is spent only on what's actually touched.
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