Realm Comprehensive Intro

An introduction to Realm in Objective-C

Transcript

1. Realm A modern database that keeps things simple Joe Anderson iOS @ Realm SD iOS SIG San Diego 10/27/2014
2. Why Realm was created Eliminate complexity Build & maintain apps faster
3. Why Now?
4. Core Data Full featured & mature 10+ years old ORM for SQLite Slow Complex and difficult to learn/debug Apple only
5. SQLite Faster than Core Data Optimized for iOS Cross Platform 14+ years old Bad User Experience Manual mapping and queries Lack of thread safety
6. What is Realm exactly? Fast, zero-copy, embedded database NoSQL Full ACID Transactions Multithreading Friendly Universal Data - Cross Platform w/ C++ Core For Objective-C, Swift, Android
7. Model Simplicity @interface Person : RLMObject @property NSString *name @property NSString *saying @end
8. Model Simplicity @interface Dog : RLMObject @property NSString *name @property int *age @end RLM_ARRAY_TYPE(Dog) @interface Person : RLMObject @property NSString *name @property NSString *saying @property RLMArray<Dog> *dogs @end
9. Model Simplicity RLMRealm *realm = [RLMRealm defaultRealm] [realm beginWriteTransaction] Person *celebrity = [Person new] celebrity.name = @“Sweet Brown” celebrity.saying = @“Ain’t nobody got time for that” [realm addObject:celebrity] [realm commitWriteTransaction]
10. Queries RLMResults *allPeople = [Person allObjects]
11. Queries with Predicates RLMResults *internetCelebs = [Person objectsWhere:@''type = 'internet' AND name BEGINSWITH 'S''']; NSPredicate *tonsOfViewsPred = [NSPredicate predicateWithFormat:@''views > %@'', @''10000000'']; RLMResults *superStars = [internetCelebs objectsWithPredicate:tonsOfViewsPred];
12. How its possible Most are building on top of SQLite zero copy architecture bitpacking reduces memory usage up to 90% caching and vectorization makes it faster than native C universal data representation from multiple languages Photo by Natalie Lucier https://flic.kr/p/6vUu56
13. Benchmarks
14. Queries
15. Counts
16. Common use cases Offline mode Caching (JSON/Object Mapping) Upload later Predictive Data Games Wearables Bluetooth Low Energy
17. JSON Mapper { name: “Sweet Brown”, saying: “Ain’t nobody got time for that”, dogs: [ { name: “Petey”, age: 1 }, { name: “Lucy”, age: 5 } ] …
18. JSON Mapper Works with any object not just JSON. Key-Value [realm beginWriteTransaction]; [Person createInDefaultRealmWithObject:personFromApi]; [realm commitWriteTransaction];
19. User Stories
20. Breezeworks “Run your entire service business from your phone” Uses Realm to embed & query large databases of tax rates & service codes 2m raised so far breezeworks.com j.mp/realm-breezeworks
21. Beanflow Full POS & inventory app (w/ offline mode) Uses Realm as network cache for all data “I don’t have any plans to go back to Core Data anytime soon. I really like Realm” sebastiandobrincu.com www.beanflow.com
22. Cloth Personal outfit diary Popular app with large user base Uses Realm for all data handling took over 2 year-old codebase and ported it to Realm in 1 day clothapp.com reallyseth.com
23. How to get started? Demo
24. Biggest mistakes people make when implementing Realm Creating foreign keys rather than thinking object based Ask whats the faulting model? People aren’t used to thinking of their objects in memory when it comes to databases
25. Migrations //v1 @interface Person : RLMObject @property NSString *firstName; @property NSString *lastName; @property int age; @end //v2 @interface Person : RLMObject @property NSString *fullName; @property int age; @end
26. Minimum Migration [RLMRealm setSchemaVersion:1 withMigrationBlock:^(RLMMigration *migration, NSUInteger oldSchemaVersion) { // We haven’t migrated anything yet, so oldSchemaVersion == 0 if (oldSchemaVersion < 1) { // Nothing to do! // Realm will automatically detect new properties and removed properties // And will update the schema on disk automatically } }];
27. Migrating Data [RLMRealm setSchemaVersion:1 withMigrationBlock:^(RLMMigration *migration, NSUInteger oldSchemaVersion) { if (oldSchemaVersion < 1) { // The enumerateObjects:block: method iterates // over every 'Person' object stored in the Realm file [migration enumerateObjects:Person.className block:^(RLMObject *oldObject, RLMObject *newObject) { // combine name fields into a single field newObject[@"fullName"] = [NSString stringWithFormat:@"%@ %@", oldObject[@"firstName"], oldObject[@"lastName"]]; }]; } }];
28. Work in progress Change notifications/Live results sets Delete Rules Bi-directional relationships Open Source Core Enhanced Data Browser Sync
29. Questions? joe@realm.io @anderson760
30. Questions answered Fetching in Core Data vs Realm? Core Data, writes the query, builds object graph, overhead there. For us, running the query builds up an array of row indexes. None of the data is loaded until you access it. Whats the difference between Realm & faulting exactly? In Core Data after faulting, when you access the object it fully loads and caches the object. With Realm we lazy load each value as you read it. How do we handle binary data, like optimization with images? We don’t do anything with that, we also don’t recommend storing large amounts of binary data in a realm What happens when you run out of storage while doing a migration? Full ACID guarantees, so the migration will fail and data is safe in its existing state, not overwritten