Tips & Tricks with Realm on iOS

Transcript

1. Tips & Tricks com Realm no iOS Rafael Kellermann Streit @rafaelks 20 de julho de 2017 TDC São Paulo
2. Rocket.Chat Open source chat platform • Open source • 10MM+ users • 100K+ servers deployed • Native apps for iOS and Android
3. Rocket.Chat
4. Realm? • Open source database framework • Complete replacement of Core Data / SQLite • Based on ORM model • Fast performance, simple API, thread safe • Cross-platform
5. Realm() let realm = try? Realm()
6. Object final class Dog: Object { dynamic var name: String? dynamic var age: Int = 0 dynamic var createdAt: Date? }
7. Start // Create a Dog instance let dog = Dog() dog.name = "Foobar" dog.age = 5 dog.createdAt = Date() // Persist data in Realm realm.write { realm.add(dog) }
8. Problem #1 Update UI with tons of single changes via socket
9. Server App Socket App connection
10. Server App user1 changed to away user2 changed to busy user3 changed to online user4 changed to invisible user5 changed to online user6 changed to away user7 changed to busy Status update of users Socket messages
11. App user1 changed to away Status update of users user2 changed to busy user3 changed to online user4 changed to invisible user5 changed to online user6 changed to away user7 changed to busy Realm user1.status = away user2.status = busy user3.status = online user4.status = invisible user5.status = online user6.status = away user7.status = busy Database update
12. ViewModel or ViewController Realm user1.status = away user2.status = busy user3.status = online user4.status = invisible user5.status = online user6.status = away user7.status = busy Status update of users UI update notificationBlock() Notify new updates
13. Notification block token = query.addNotificationBlock { [weak self] changes in switch changes { case .initial(let results): break case .update(let results, let deletions, let insertions, let modifications): break case .error: break } }
14. Problem #2 Reuse model mapping & model handling code
15. Base model class BaseModel: Object { dynamic var identifier: String? override static func primaryKey() -> String? { return "identifier" } }
16. Handle model changes
17. Protocols protocol ModelHandler { func add(_ values: JSON, realm: Realm) func update(_ values: JSON, realm: Realm) func remove(_ values: JSON, realm: Realm) } Handle updates
18. Extensions guard let msg = result.msg else { return } guard let identifier = result.result["id"].string else { return } let fields = result.result["fields"] switch collection { case "users": User.handle(msg: msg, primaryKey: identifier, values: fields) break case "subscriptions": Subscription.handle(msg: msg, primaryKey: identifier, values: fields) break default: break } Handle updates add, change, remove
19. Extensions extension ModelHandler where Self: BaseModel { static func handle(msg: ResponseMessage, primaryKey: String, values: JSON) { Realm.execute({ (realm) in var object: Self! if let existentObject = realm.object(ofType: Self.self, forPrimaryKey: primaryKey as AnyObject) { object = existentObject } if object == nil { object = Self() object.setValue(primaryKey, forKey: Self.primaryKey() ?? "") } switch msg { case .added: object.add(values, realm: realm) break case .changed: object.update(values, realm: realm) break case .removed: object.remove(values, realm: realm) break default: object.update(values, realm: realm) break } }) } } Handle updates
20. Handle model mapping JSON > Realm
21. Protocols protocol ModelMappeable { func map(_ values: JSON, realm: Realm?) } Model mapping
22. Protocols extension User: ModelMappeable { func map(_ values: JSON, realm: Realm?) { if self.identifier == nil { self.identifier = values["_id"].string } if let username = values["username"].string { self.username = username } if let status = values["status"].string { self.status = UserStatus(rawValue: status) ?? .offline } } } Model mapping
23. Final tip Avoid using main-thread to call Realm
24. Wrapper extension Realm { static func execute(_ execution: @escaping (Realm) -> Void, completion: VoidCompletion? = nil) { var backgroundTaskId: UIBackgroundTaskIdentifier? let name = "chat.rocket.realm.background" backgroundTaskId = UIApplication.shared.beginBackgroundTask(withName: name, expirationHandler: { _ in backgroundTaskId = UIBackgroundTaskInvalid }) if let backgroundTaskId = backgroundTaskId { DispatchQueue.global(qos: .background).async { _ in guard let realm = try? Realm() else { return } try? realm.write { execution(realm) } DispatchQueue.main.async { completion?() } UIApplication.shared.endBackgroundTask(backgroundTaskId) } } } } Background execution
25. Wrapper Realm.execute({ (realm) in let users = realm.objects(User.self) users.setValue("offline", forKey: “status") }, completion: { done() }) Example
26. Rocket.Chat.iOS github.com/RocketChat/Rocket.Chat.iOS
27. Thanks! •@rafaelks •github.com/RocketChat