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MVVM(DC): Taming your architecture

MVVM(DC): Taming your architecture

Everyone is well aware of most of the different architectures available out there and jump here and there trying to be on the «latest and trendiest architecture»; which is ok, sadly though, most of the time we are left with lots of gaps and wondering how exactly our apps fit into this architecture or the other with no clear answer.

This talk will try to help fill some of the gaps in between MVVM via introducing some concepts that even though they are not new; giving them a name and an explanation into how they fit and tie things together helps others understand better a simple yet very helpful architecture like MVVM.

Esteban Torres

February 16, 2017

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  1. Not only this but we also lack certain «pieces» along

    this architectures or lack a clear understanding of where things belong Esteban Torres - @esttorhe, MobOS, 2017 4
  2. What DO we have? (some of them at least) Esteban

    Torres - @esttorhe, MobOS, 2017 6
  3. MVC Verdict: By its basic definition not good enough for

    complex apps Esteban Torres - @esttorhe, MobOS, 2017 10
  4. VIPER 4 View 4 Interactor (Use Cases) 4 Presenter 4

    Entity 4 Router Esteban Torres - @esttorhe, MobOS, 2017 12
  5. VIPER Verdict: «Chunky» projects, very testable, clear separation of concerns,

    sometimes «overly» complex Esteban Torres - @esttorhe, MobOS, 2017 13
  6. ViewModel 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, MobOS, 2017 18
  7. class ViewModelA { private let model: Model var formattedCurrency: String…

    var formattedProperty1: Double… var formattedProperty2: String… … … init(withModel model: Model) … func getModels(completion:([Model]) -> ()) -> Void { API.request(.GetModels) { jsonResponse in // Parse the JSON response here let models = … completion(models) } } } Esteban Torres - @esttorhe, MobOS, 2017 37
  8. 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, MobOS, 2017 39
  9. 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, MobOS, 2017 44
  10. 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, MobOS, 2017 45
  11. «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, MobOS, 2017 48