Rocket Data SLUG Talk

Slides for the presentation given at SLUG on July 21st, 2016. http://www.meetup.com/swift-language/events/232135313/

Transcript

1. Keeping Immutable Models Consistent Peter Livesey July 21st, 2016
2. Core Data
3. Immutable Models • Thread-safe • Performant • Easier to debug • Promote functional code https://realm.io/news/slug-keith-smiley-embrace-immutability/
4. How do I keep things consistent? class MyViewController: UIViewController { let personModel: PersonModel func comeOnline() { personModel.isOnline = true refreshView() } }
5. Our Requirements • Immutable, thread-safe models • Consistency • Non-blocking access on all reads and writes • Simple eviction strategy • Scales well • Easy migrations
6. Data A caching and consistency solution for immutable models.
7. How does this look in a view controller? class MyViewController: UIViewController { let dataProvider = DataProvider<PersonModel>() func viewDidLoad() { super.viewDidLoad() dataProvider.fetchDataFromCache(cacheKey: self.id) { (_, _) in self.refreshView() } MyNetworkManager.fetchPerson(id: self.id) { (model, error) in if let model = model { self.dataProvider.setData(model) self.refreshView() } } } }
8. How to Respond to Changes class MyViewController: UIViewController { func dataProviderHasUpdatedData<T>(dataProvider: DataProvider<T>, context: Any?) { refreshView() } }
9. General Architecture
10. Consistency Manager DataProvider<T> Consistency Manager listenForUpdates() modelUpdated(model) updateModel(model)
11. How an Update Works
12. How an Update Works
13. How an Update Works
14. What’s Required for Models protocol Model { var modelIdentifier: String? { get } func isEqualToModel(model: Model) -> Bool func map(transform: Model -> Model?) -> Self? func forEach(visit: Model -> Void) }
15. Collections
16. Collections Ordered Easy to Edit Syncable
17. The Cache
18. The Cache public protocol CacheDelegate { func modelForKey<T: Model>(cacheKey, context, completion) func setModel<T: Model>(model, forKey cacheKey, context) func collectionForKey<T: Model>(cacheKey, context, completion) func setCollection<T: Model>(collection, forKey cacheKey, context) func deleteModel(model, forKey cacheKey, context) }
19. Denormalized vs Normalized Models [ 34: MessageModel, 12: PersonModel, 42: MessageModel, 51: PersonModel ]
20. Rocket Data
21. Thank you Thanks to Nick Snyder, Nitesh Donti, and the Voyager, Groups and Lynda teams for making Data happen