Core Data Fundamentals

I gave a talk on Core Data in a Nutshell and its concurrency rules.

Transcript

1. Core Data Fundamentals
   - @ajithrnayak
   

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2. Core Data Vs Developers
   

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3. Core Data Stack
   NSPersistentStoreCoordinator
   SQLite
   NSPersistentContainer
   NSManagedObjectContext
   NSPersistentStore
   NSManagedObjectModel
   App
   

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4. NSManagedObjectContext
   • Like a scratchpad
   
   
   • fetch, change, add and delete
   
   
   • Create more than one contexts
   
   
   • Updates persistent store
   

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5. Concurrency policies
   ConcurrencyType
   NSPrivateQueueConcurrencyType
   

   (background queue)
   NSMainQueueConcurrencyType
   

   (application’s main queue)
   

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6. perform(_:)
   • asynchronous method
   
   
   • gets wrapped in a autorelease pool.
   performAndWait(_:)
   • synchronous method
   
   
   • will block the calling thread
   
   
   • does not wrap the block in an
   

   autorelease pool.
   

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7. Summary
   • A managed object context is tied to a serial queue.
   
   
   • Create only two contexts for simplicity.
   
   
   • Concurrency types are two but contexts can be many.
   
   
   • Context executes on a “private” queue.
   
   
   • Performance heavy operations should be performed on the background queue.
   
   
   • Don’t pass NSManagedObject instances between queues.
   
   
   • To avoid unnecessary saves, be aware of automatically triggered broadcasts.
   

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8. Thank you
   

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