Everyday CoreData

My CoreData talk at CodersOnly on March 16, 2016

Transcript

1. Everyday CoreData Pat Zearfoss
2. About Me • Pat Zearfoss • CircleBack on the app store • Running on a CoreData stack for better than a year. • @patzearfoss on Twitter.
3. End User License Agreement • My suggestions may not be 100% right for all situations • CoreData elicits a lot of opinions in the community. • Your app may not fit the same patterns and models
4. Lets Go
5. Things I’ll talk about • Frameworks and tools • Model design • App architecture • Testing • Debugging tools
6. CoreData Review
7. CoreData Review • A way of persisting data in Cocoa applications • Not a database • Well, it kind of is, but not necessarily • On label usage is “object graph persistence”
8. Object Graph
9. CoreData Pieces • NSManagedObjectModel • NSPesistentStoreCoordinator • NSManagedObjectContext • NSManagedObject
10. Tip #1 Once you understand CoreData, use a framework (or write one) to make life easier.
11. There’s tons • Magical Record • BNRCoreData • RestKit
12. Why • It’ll help you simplify all the stuff you’ll do anyway. • CoreData can be . . . wordy.
13. Creating a new instance if let eDesc = NSEntityDescription.entityForName(“Contact”, inManagedObjectContext: context) { let contact1 = Contact(entity: contactDescription, insertIntoManagedObjectContext:context) }
14. A basic fetch let fetchRequest = NSFetchRequest(entityName: “Contact”) fetchRequest.sortDescriptors = [NSSortDescriptor(key: “lastName”, ascending: true)] fetchRequest.predicate = NSPredicate(format: “isFavorite = YES”) if let context = context { do { try contacts = context. executeFetchRequest(fetchRequest) as! [Contact] } catch { print (“couldn’t load contacts”) } }
15. The app delegate eyebleed
16. Creating an instance - MR if let contact1 = Contact.MR_createEntityInContext(context) Fetch if let fetchedContacts = Contact.MR_findAllSortedBy(“lastName”, ascending: true, inContext: context) as? [Contact]
17. Eyebleed cured MagicalRecord.setupCoreDataStack()
18. Demo 1
19. More tools • SimPholders • CoreDataEditor • SQLPro or other Sqlite tool
20. Modeling • Your managed model is a database, but it also isn’t. You have to make it work right for you.
21. Tip #2 Design for your app. Don’t feel the need to appease the database gods.
22. Demo 2
23. Tip #3 Use NSManagedObjectContexts liberally • Creating a new context to fetch objects, passing the ids to a main context for use on the UI. • Doing expensive operations in background queues • Creating a throw-away editing context.
24. Demo 3
25. Tip #4 NSFetchedResultsController can be your best friend • NSFetchedResultsController manages the results of a fetch into a context.
26. NSFetchedResultsController • Keeping a UI updated with changes from the internet. • Use fetched results controllers to manage all communication with a web backend.
27. Demo 4
28. Architectural patterns from fetched results controllers
30. Testing • You don’t really care about persistence • You just want to test this object, controller, view model, etc.
31. Tip #5 Use an in-memory store for testing • Sets up the same scheme you have in memory. • Quick and easy to set up an tear down between tests
32. Demo 5
33. Debugging
34. Tip #6 Learn and use the CoreData environment variables
35. Useful environment variables • com.apple.CoreData.SQLDebug [1,2,3] • com.apple.CoreData.SyntaxColoredLogging 1 • com.apple.CoreData.ConcurrencyDebug 1 • (not ThreadDebug) • com.apple.CoreData.MigrationDebug
36. Demo 6
37. Tip #7 Use the CoreData tool in instruments
38. Demo 7 CircleBack App
39. Tip #8 Other people have really good ideas • Saul Mora - original author of MagicalRecord • Marcus Zarra - wrote many a book on CoreData • objc.io on CoreData • WWDC Material (obvi)
40. Recap • Find a good framework to help you. • Design a model that fits your app’s needs • Make use of NSManagedObjectContext • Use NSFetchedResultsControllers
41. Recap • Use in memory stores for testing • CoreData runtime arguments are your friend • Make use of Instruments • Read good material
42. ?s and Thanks! • pzearfoss@gmail.com • @patzearfoss