I really like CoreData. I think it's a great piece of software (I know this is a controversial opinion in some circles ;)). My only pet peeve with it has been the string-based querying API based on NSPredicate. It is a major source of bugs/crashes and doesn't really fit nicely in the modern strongly-typed world of Swift. I built PredicateKit as a lightweight replacement for NSPredicateKit (specifically for CoreData) that makes writing predicates as safe and pleasant as writing native Swift code.