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.

Transcript

1. MVVM(DC): Taming your architecture Esteban Torres - @esttorhe, MobOS, 2017 1
2. Which architecture should I use? Esteban Torres - @esttorhe, MobOS, 2017 2
3. What is the «Problem»? Esteban Torres - @esttorhe, MobOS, 2017 3
4. 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
5. What DO we have ? Esteban Torres - @esttorhe, MobOS, 2017 5
6. What DO we have? (some of them at least) Esteban Torres - @esttorhe, MobOS, 2017 6
7. MVC Esteban Torres - @esttorhe, MobOS, 2017 7
8. Esteban Torres - @esttorhe, MobOS, 2017 8
9. The «Problem» of MVC Esteban Torres - @esttorhe, MobOS, 2017 9
10. MVC Verdict: By its basic definition not good enough for complex apps Esteban Torres - @esttorhe, MobOS, 2017 10
11. VIPER Esteban Torres - @esttorhe, MobOS, 2017 11
12. VIPER 4 View 4 Interactor (Use Cases) 4 Presenter 4 Entity 4 Router Esteban Torres - @esttorhe, MobOS, 2017 12
13. VIPER Verdict: «Chunky» projects, very testable, clear separation of concerns, sometimes «overly» complex Esteban Torres - @esttorhe, MobOS, 2017 13
14. MVVM Esteban Torres - @esttorhe, MobOS, 2017 14
15. Model Esteban Torres - @esttorhe, MobOS, 2017 15
16. View Esteban Torres - @esttorhe, MobOS, 2017 16
17. ViewModel Esteban Torres - @esttorhe, MobOS, 2017 17
18. 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
19. What do we have? Esteban Torres - @esttorhe, MobOS, 2017 19
20. MVC Esteban Torres - @esttorhe, MobOS, 2017 20
21. Esteban Torres - @esttorhe, MobOS, 2017 21
22. VIPER Esteban Torres - @esttorhe, MobOS, 2017 22
23. Esteban Torres - @esttorhe, MobOS, 2017 23
24. MVVM Esteban Torres - @esttorhe, MobOS, 2017 24
25. Esteban Torres - @esttorhe, MobOS, 2017 25
26. We DON'T have a place Esteban Torres - @esttorhe, MobOS, 2017 26
27. Esteban Torres - @esttorhe, MobOS, 2017 27
28. ¯\_(ϑ)_/¯ What does this mean? Esteban Torres - @esttorhe, MobOS, 2017 28
29. Esteban Torres - @esttorhe, MobOS, 2017 29
30. Let's figure it out using MVVM Esteban Torres - @esttorhe, MobOS, 2017 30
31. Network layer Esteban Torres - @esttorhe, MobOS, 2017 31
32. Esteban Torres - @esttorhe, MobOS, 2017 32
33. !❓ Esteban Torres - @esttorhe, MobOS, 2017 33
34. ! Esteban Torres - @esttorhe, MobOS, 2017 34
35. Esteban Torres - @esttorhe, MobOS, 2017 35
36. ! Esteban Torres - @esttorhe, MobOS, 2017 36
37. 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
38. ! Esteban Torres - @esttorhe, MobOS, 2017 38
39. 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
40. DataControllers Esteban Torres - @esttorhe, MobOS, 2017 40
41. Esteban Torres - @esttorhe, MobOS, 2017 41
42. It worked Esteban Torres - @esttorhe, MobOS, 2017 42
43. Esteban Torres - @esttorhe, MobOS, 2017 43
44. 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
45. 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
46. So… what did we do? ! Esteban Torres - @esttorhe, MobOS, 2017 46
47. Conclusion Esteban Torres - @esttorhe, MobOS, 2017 47
48. «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
49. Questions? Esteban Torres - @esttorhe, MobOS, 2017 49
50. Thanks Esteban Torres - @esttorhe, MobOS, 2017 50