US Mercari iOS App Architecture and Dependency Injection

Transcript

1. Mercari Tech Conf 2017 Software Engineer (iOS) Yoichi Tagaya US版Mercari iOSアプリの アーキテクチャーとDependency Injection US Mercari iOS App - Architecture and Dependency Injection
2. About Me Yoichi Tagaya Author of Swinject - Dependency injection framework - 1800+ GitHub stars - 5 maintainers - De facto standard in Swift @yoichitgy
3. Swinject Users (GitHub Cloners) * https://github.com/Swinject/Swinject
4. Swinject Users (CocoaPods) * https://cocoapods.org/pods/Swinject
5. Swinject Users (Job Descriptions) - Atlassian - Implement unit tests and performance tests in Objective-C and Swift using XCTest, OCMock, Swinject... - https://www.smartrecruiters.com/Atlassian/93336663-ios-developer - MealPass - Familiarity with dependency injection libraries such as swinject - http://garysguide.com/jobs/up0gwed/Software-Engineer-at-MealPass-New-York-NY - Location Labs - We are using in our iOS products, including Cocoapods, Typhoon/Swinject, Realm, PromiseKit, Alamofire, Amplitude... - https://www.latitude.work/locationlabs/emeryville/senior-software-engineer-ios - МАДЖЕСТИ - 1. Realm, 2. Dependency injection (Swinject), 3. Работа с платежными... - https://voronezh.hh.ru/vacancy/17552731 - And more… (Mercari too)
6. About Me at Mercari Yoichi Tagaya iOS Engineer - Mainly US Mercari App - Since January, 2017
7. About Me in 2017 Jan-Feb Mar Apr-Jun Jul Aug-Sep
8. About Me in 2017 Jan-Feb Mar Apr-Jun Jul Aug-Sep Work Globally at Mercari!!
9. 2017 in US
10. Brand New US Mercari App
11. Brand New US Mercari App Old: JP App Base
12. Brand New US Mercari App New codebase New design New architecture
13. New Architecture: MVVM + Repository Pattern Model View ViewModel Service Repository Entity UIView/UIViewController Protocol Buffers Class with Protocol Class with Protocol Reference Signal (ReactiveSwift)
14. New Architecture: MVVM + Repository Pattern Model View ViewModel Service Repository Entity UIView/UIViewController Protocol Buffers Class with Protocol Class with Protocol Class with Protocol Class with Protocol Reference Signal (ReactiveSwift) Use protocol as interface
15. So, You Know... Dependency Injection Inversion of Control for resolving dependencies You create what you use. ↺ What you use are created and passed.
16. Mocking with Dependency Injection Implementation Concrete Type External System Mock Easy to swap, easy to test Protocol
17. More Advantages of Dependency Injection 1. Use dependency without its knowledge 2. Clarify design of dependency 3. Promote modularization 4. Avoid vendor lock in
18. Dependency Injection in WWDC • WWDC 2016 • Improving Existing Apps with Modern Best Practices* • WWDC 2017 (indirectly) • Engineering for Testability** * https://developer.apple.com/videos/play/wwdc2016/213/ ** https://developer.apple.com/videos/play/wwdc2017/414/
19. Why Dependency Injection Framework? Dependency Injection is... Mendokusai ~Tiresome~
20. What We Need Is... Simple solution
21. What We Need Is... Let’s make a simple DI container!
22. Wait, What’s DI (Dependency Injection) Container? DI Container Register the dependency graph A B C D E F G H I Dependency graph let a = … Resolve dependencies upon your request
23. Demo Demonstrated playground program: https://gist.github.com/yoichitgy/2a27b96a3ea4a8eb595059858d95fb2a
24. How to Use Swinject
25. How to Use Swinject import Swinject let container = Container() container.register(Animal.self) { _ in Cat() } container.register(PetOwner.self) { resolver in PetOwner(pet: resolver.resolve(Animal.self)!) } DI Container Register Use resolver to resolve inside a closure
26. import Swinject let petOwner = container.resolve(PetOwner.self)! How to Use Swinject Resolve DI Container Same as the demo
27. How to Practically Organize Dependency Definitions • Use Assembly and Assembler • Production app has too many dependencies to define at once
28. Swinject Assembly and Assembler ItemDetailAssembly HomeAssembly APIClientAssembly FirebaseAssembly CrashlyticsAssembly DateAssembly View/ViewModel Service Assembler Container
29. final class HomeAssembly: Assembly { func assemble(container: Container) { container.register(HomeViewModelProtocol.self) { resolver in let dependency = ( resolver.resolve(APIClientProtocol.self)!, resolver.resolve(CrashlyticsAdapterProtocol.self)! ) return HomeViewModel(dependency: dependency) } container.register(HomeViewController.self) { resolver in let vc = HomeViewController.instantiateFromStoryboard() vc.viewModel = resolver.resolve(HomeViewModelProtocol.self)! return vc } } } How to Use Assembly Group related dependency definitions by Assembly
30. let container = Assembler([ // Home HomeAssembly(), // ItemDetail ItemDetailAssembly(), // APIClient APIClientAssembly(), // Util DateAssembly(), // Adapter CrashlyticsAssembly(), FirebaseAssembly(), ]).resolver How to Use Assembler Assembler Container (as Resolver) Array of Assemblies
31. Dependency Injection is... Mendokusai ~Tiresome~
32. Dependency Injection is... Mendokusaku nai ~Not tiresome~ Swinject Assembly/Assembler With
33. Demo Mendokusaku nai ~Not tiresome~ Demonstrated Xcode 9 project (zip): https://goo.gl/5qt6Xr
34. Summary • Architecture: MVVM + Repository Pattern • Dependency Injection: Mendokusai ~ Tiresome ~ • Dependency Injection Container X
35. Thank You Feel free to talk to me in the other room for questions about this talk or iOS engineering at Mercari