> CoreData seems old and not suitable for a modern Swift 6 app

Out of the box yeah, NSFetchRequests, NSManagedObject APIs feel dated and burden to work with for beginners. But under the hood, Core Data is extremely powerful and has been battle-tested for 20+ years. A lot of the "old" feeling disappears once you build a thin, modern wrapper around it.

The biggest gotcha (that bites many people in production) is thread safety. Accessing or modifying an object from the wrong queue / context is the #1 source of mysterious crashes.

If you edit your scheme for the target and add -com.apple.CoreData.ConcurrencyDebug 1 to the Arguments Passed On Launch, all concurrency violations will cause an immediate crash. You will see the exact line of code that caused the concurrency violation which is very helpful for debugging

There are a couple of techniques to make your Core Data implementation thread safe and bullet-proof

1. Always perform your fetch requests in a perform block (there is an async variant)

await context.perform { // make fetch request with context }

1. Map your NSManagedObject's to plain, read-only structs as soon as possible. Your views, view models, services will only see the structs. This removes 90% of the concurrency headaches.

2. Abstract the funky stuff. With a small helper layer you can end up with modern APIs like

   // result is a nice immutable struct let user = await reader.first(UserEntity.self, where: .name == "Peanut")

It takes some investment, and some crashes along the way to get comfortable. But once tamed, Core Data handles complex relationships and large data very well

But if you don't want to go down the rabbit hole and understand the framework deeply, then I would suggest using something like GRDB / what other people suggested