MVVM, RxSwift and DataControllers Esteban Torres - @esttorhe, iOSCon, 2016

MVC Esteban Torres - @esttorhe, iOSCon, 2016

The «Problem» of MVC Esteban Torres - @esttorhe, iOSCon, 2016

MVVM Esteban Torres - @esttorhe, iOSCon, 2016

Model Esteban Torres - @esttorhe, iOSCon, 2016

View Esteban Torres - @esttorhe, iOSCon, 2016

ViewModel Esteban Torres - @esttorhe, iOSCon, 2016

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

What now? Esteban Torres - @esttorhe, iOSCon, 2016

Let's make some UI Esteban Torres - @esttorhe, iOSCon, 2016

And some Models struct Hops { let uuid: String let name: String? let amount: Double } Esteban Torres - @esttorhe, iOSCon, 2016

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

Network layer Esteban Torres - @esttorhe, iOSCon, 2016

Esteban Torres - @esttorhe, iOSCon, 2016

!❓ Esteban Torres - @esttorhe, iOSCon, 2016

! Esteban Torres - @esttorhe, iOSCon, 2016

! Esteban Torres - @esttorhe, iOSCon, 2016

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

! Esteban Torres - @esttorhe, iOSCon, 2016

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

Brewbot to the rescue(?)!!! Esteban Torres - @esttorhe, iOSCon, 2016

DataControllers Esteban Torres - @esttorhe, iOSCon, 2016

Esteban Torres - @esttorhe, iOSCon, 2016

But there's more… Esteban Torres - @esttorhe, iOSCon, 2016

The age of Swift Esteban Torres - @esttorhe, iOSCon, 2016

MVVM + RxSwift + DataControllers Esteban Torres - @esttorhe, iOSCon, 2016

RxSwift Esteban Torres - @esttorhe, iOSCon, 2016

! Esteban Torres - @esttorhe, iOSCon, 2016

Esteban Torres - @esttorhe, iOSCon, 2016

Esteban Torres - @esttorhe, iOSCon, 2016

Esteban Torres - @esttorhe, iOSCon, 2016

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 { 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

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

Rx Bindings Esteban Torres - @esttorhe, iOSCon, 2016

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

So… what did we do? ! Esteban Torres - @esttorhe, iOSCon, 2016

Conclusion Esteban Torres - @esttorhe, iOSCon, 2016

. "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

Questions? Esteban Torres - @esttorhe, iOSCon, 2016

Thanks Esteban Torres - @esttorhe, iOSCon, 2016