MVVM + RxSwift + DataControllers

Talk given at iOScon 2016 (https://skillsmatter.com/skillscasts/7863-mvvm-rxswift-and-datacontrollers).

How we at Brewbot.io tackled the missing «Data management» on MVVM and glued everything together with RxSwift

Transcript

1. MVVM, RxSwift and DataControllers Esteban Torres - @esttorhe, iOSCon, 2016
2. MVC Esteban Torres - @esttorhe, iOSCon, 2016
3. The «Problem» of MVC Esteban Torres - @esttorhe, iOSCon, 2016
4. MVVM Esteban Torres - @esttorhe, iOSCon, 2016
5. Model Esteban Torres - @esttorhe, iOSCon, 2016
6. View Esteban Torres - @esttorhe, iOSCon, 2016
7. ViewModel Esteban Torres - @esttorhe, iOSCon, 2016
8. class MyViewModel { // The model being «formatted» private var model: MyModel? = nil // A formatted property let amountDueText: String { var currencyFormatter = NSNumberFormatter() currencyFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle currencyFormatter.locale = NSLocale.currentLocale() return currencyFormatter.stringFromNumber(model?.amount) ?? 0) } } Esteban Torres - @esttorhe, iOSCon, 2016
9. What now? Esteban Torres - @esttorhe, iOSCon, 2016
10. Let's make some UI Esteban Torres - @esttorhe, iOSCon, 2016
11. And some Models struct Hops { let uuid: String let name: String? let amount: Double } Esteban Torres - @esttorhe, iOSCon, 2016
12. Enter ViewModels class HopsViewModel { // Model private let model: Hops // Properties var name: String { return model.name ?? "N/A" } var amount: String { // Notice how here we should convert to the user's unit (imperial / metric) return "\(model.amount) g" } init(withHop hop: Hop) … } Esteban Torres - @esttorhe, iOSCon, 2016
13. Network layer Esteban Torres - @esttorhe, iOSCon, 2016
14. Esteban Torres - @esttorhe, iOSCon, 2016
15. !❓ Esteban Torres - @esttorhe, iOSCon, 2016
16. ! Esteban Torres - @esttorhe, iOSCon, 2016
17. ! Esteban Torres - @esttorhe, iOSCon, 2016
18. class ViewModelA { private let model: Model var formattedCurrency: String… var formattedProperty1: Double… var formattedProperty2: String… … … init(withModel model: Model) … func getModels(closure:([Model]) -> ()) -> Void { API.request(.GetModels) { jsonResponse in // Parse the JSON response here let models = … closure(models) } } } Esteban Torres - @esttorhe, iOSCon, 2016
19. ! Esteban Torres - @esttorhe, iOSCon, 2016
20. MVVM …an abstraction of the view exposing public properties and commands… In the view model, the binder mediates communication between the view and the data binder. The view model has been described as a state of the data in the model.1 1 http://wayback.archive.org/web/20080201101909/http://www.acceptedeclectic.com/2008/01/model-view-viewmodel- pattern-for-wpf.html Esteban Torres - @esttorhe, iOSCon, 2016
21. Brewbot to the rescue(?)!!! Esteban Torres - @esttorhe, iOSCon, 2016
22. DataControllers Esteban Torres - @esttorhe, iOSCon, 2016
23. Esteban Torres - @esttorhe, iOSCon, 2016
24. But there's more… Esteban Torres - @esttorhe, iOSCon, 2016
25. The age of Swift Esteban Torres - @esttorhe, iOSCon, 2016
26. MVVM + RxSwift + DataControllers Esteban Torres - @esttorhe, iOSCon, 2016
27. RxSwift Esteban Torres - @esttorhe, iOSCon, 2016
28. ! Esteban Torres - @esttorhe, iOSCon, 2016
29. Esteban Torres - @esttorhe, iOSCon, 2016
30. Esteban Torres - @esttorhe, iOSCon, 2016
31. Esteban Torres - @esttorhe, iOSCon, 2016
32. class ViewModel { // Hold a reference to our DataController private let dataController: DataController // Hold a reference to the model we will be getting private var model: Model? func getModel(id: Int) -> Observable<Model> { return Observable.create { observer in dataController.getModel(id) .subscribe(onNext: { [unowned self] model in self.model = model // If we need to format something else we should do it here observer.onNext(self.model) }, onError: { error in // Maybe properly format the error to the user here as well observer.onError(error) } ).addDisposableTo(disposeBag) } } } Esteban Torres - @esttorhe, iOSCon, 2016
33. class ViewController: UIViewController { // Retain a reference to our ViewModel private let viewModel: ViewModel func loadData() -> Void { self.viewModel.loadModel() .subscribeOn(MainScheduler.instance) .subscribe(onNext: { [unonwed self] viewModel in // Update your `UI` accordingly self.nameLabel.text = viewModel.formattedName self.amountLabel.tet = viewModel.hopsAmount }, onError: { error in } }) .addDisposableTo(disposeBag) } } Esteban Torres - @esttorhe, iOSCon, 2016
34. Rx Bindings Esteban Torres - @esttorhe, iOSCon, 2016
35. class ViewController: UIViewController { // Retain a reference to our ViewModel private let viewModel: ViewModel // Binding function override func viewDidLoad() { super.viewDidLoad() self.bindComponents() } } private extension ViewController { func bindComponents() -> Void { self.viewModel .formattedName .bindTo(self.nameLabel.rx_text) .addDisposableTo(disposeBag) self.viewModel .hopsAmount .bindTo(self.amountLabel.rx_text) .addDisposableTo(disposeBag) } } Esteban Torres - @esttorhe, iOSCon, 2016
36. So… what did we do? ! Esteban Torres - @esttorhe, iOSCon, 2016
37. Conclusion Esteban Torres - @esttorhe, iOSCon, 2016
38. . "That was the worst idea EVER… BUT seeing how badly they tackled that problem gave me an idea about how to actually make it work." Esteban Torres - @esttorhe, iOSCon, 2016
39. Questions? Esteban Torres - @esttorhe, iOSCon, 2016
40. Thanks Esteban Torres - @esttorhe, iOSCon, 2016