Trends & Patterns

Talk given at CocoaHeads Strasbourg.

Transcript

1. FRÉDÉRIC MAQUIN @EPHREAD CocoaHeads Strasbourg NOVEMBER 17TH, 2016 PATTERNS Trends & ! BETA
2. There are lots of competing architectural styles and design patterns. 2
3. There are lots of competing architectural styles and design patterns. (By lots I mean three, really.) 2
4. MVC CONTROLLER MODEL VIEW 3
5. MVVM VIEW MODEL MODEL VIEW (UIVIEW + UIVIEWCONTROLLER) Works best with Reactive Programming™ 4
6. VIPER PRESENTER INTERACTOR VIEW (UIVIEW + UIVIEWCONTROLLER) For the worthy only. 5 ROUTER ENTITY
7. — Well-known anonymous person MVC stands for Massive View Controller “ ” 6
8. — Soroush Khanlou MVVM is Not Very Good “ ” 7
9. — Ash Furrow MVVM is exceptionally OK “ ” 8
10. — Random Android guy on the Internet MVP is the gold standard “ ” 9
11. MVVMMVCMVPMVVMCVIPERMVVMMV CMVPMVVMCVIPERMVVMMVCMVPMV VMCVIPEMVVMMVCMVPMVVMCVIPER MVVMMVCMVPMVVMCVIPERRMVVMM VCMVPMVVMCVIPERMVVMMVCMVPM VVMCVIPERMVVMMVCMVPMVVMCVIP ERMVVMMVCMVPMVVMCVIPERMVVM 10
12. Which one should I choose? 11
13. Everyone has their own preferences, opinions and biases. 12
14. — Christian Tietze Don’t force any architectural patterns down your throat. Strive for higher testability first. “ ” 13
15. How do we strive for higher testability and higher maintainability? 14
16. SINGLE RESPONSABILITY PRINCIPLE #1 15
17. Split features across small components. One feature per component. single responsability principle 16
18. single responsability principle class UIViewController: CBCentralManagerDelegate, CLLocationManagerDelegate { var bluetoothManager: CBCentralManager! var locationManager: CLLocationManager! func viewDidLoad() { bluetoothManager.delegate = self locationManager.delegate = self } } 17
19. single responsability principle class UIViewController { var bluetoothManager: BluetoothManager! var locationManager: LocationManager! } 17
20. single responsability principle Andy Matuschak did an amazing talk on how to refactor with the SRP in mind. 18
21. #2 LOOSE COUPLING 19
22. Loose coupling allows you to test modules independently from each other. Use dependency injection to decouple modules. 20
23. The idea is to provide dependencies, rather than create/retrieve them. dependency injection 21
24. without dependency injection class Model☰ { let electricalMotor: ElectricalMotor = InductionMotor() } " Tight Coupling! 22
25. class Model☰ { let electricalMotor: ElectricalMotor init(electricalMotor: ElectricalMotor) { self.electricalMotor = electricalMotor } } class Model☰ViewController { var electricalMotor: ElectricalMotor! } CONSTRUCTOR METHOD with dependency injection 23
26. class Model☰ { let electricalMotor: ElectricalMotor = Injector.resolve(ElectricalMotor.self) } # BAD! ⚠ Inversion of Control is important! with dependency injection 24
27. tools for dependency injection TYPHOON DIP SWINJECT* [] & * my favorite! CLEANSE 25
28. What about decoupling the app flow? performSegueWithIdentifier("startCar", sender: self) STORYBOARD pushViewController(CarStarter(), animated: true) presentViewController(CarStarter(), animated: true, completion: nil) OLD FASHIONED WAY 26
29. There is a way. 27
30. New Kid on the Block THE COORDINATOR 28
31. The coordinator plugs into existing patterns. Except for VIPER, where it’s already there. 29
32. MVVM-C MVC-C
 WHATEVER-C 30
33. The app coordinator handles the navigation flow, decoupling the controllers from each others. coordinator 31
34. coordinator APP COORDINATOR AUTHENTICATION COORDINATOR FEED COORDINATOR […] AUTHENTICATION VIEW CONTROLLER PROFILE VIEW CONTROLLER FEED VIEW CONTROLLER DETAIL VIEW CONTROLLER 32
35. So, which pattern should you choose? 33
36. Rule of % Very simple app App with a lot of UI states and asynchronous behaviors Very complex app built with a large team MVC MVVM VIPER 34 Not meant to be taken as a hard rule.
37. Don’t try too hard to pick a fitting pattern. Try harder to keep the code clear, testable and maintainable, because… 35
38. — Christian Tietze You need knowledge and experience and creativity. When you can come up with something on your own, you can interpret the rules of VIPER, layered architecture, or whatever else you find on the web properly. You can pick up new ideas and come up with solutions on your own instead of looking for a fitting solution out there. “ ” 36
39. Questions ? 37
40. 38 resources iOS Architecture Patterns @borlov MVVM is Not Very Good @khanlou MVVM is Exceptionally OK @ashfurrow MVVM Is Quite Okay at What It Is Supposed to Do @ctietze Let’s Play: Refactor the Mega-Controller @andy_matuschak
41. 39 resources Coordinators Redux @khanlou Improve your iOS Architecture with FlowControllers @merowing Coordinators with Storyboards @apokrupto