MVVM + RxSwift + DataControllers

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

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Esteban Torres

May 27, 2016
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Transcript

  1. 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
  2. 11.

    And some Models struct Hops { let uuid: String let

    name: String? let amount: Double } Esteban Torres - @esttorhe, iOSCon, 2016
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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