iOS Conf SG - 2022 - Dependency Injection at scale

Building a feature in an app consisting of 95+ modules is complicated and leads to dependency management hell. Splitting a module into a public interface and a separate implementation framework for the interface allows to create simpler deps management and improve build times.

https://www.youtube.com/watch?v=a1KvjxNVEq8&list=PLED4k3CZkY9R9mhRW5V74gS9cVTp28CbK

Transcript

1. Dependency Injection at scale iOS Conf SG 2022 Maciej Piotrowski | Allegro.pl
2. 9+ years iOS development Mobile Core Team @ allegro “I make devs’ lives easier” Maciej Piotrowski
3. 20 million customers each month one of top ten most visited e-commerce sites worldwide mobile apps big chunk of traf fi c the most popular product search engine in Poland
4. XcodeGen Bazel Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away steve
5. OVERVIEW: Steve provides you a convenient way to solve daily 👨💻 development problems and complete repetitive tasks. USAGE: steve <subcommand> OPTIONS: --version Shows the version -h, --help Shows help information SUBCOMMANDS: fixme Fixes most common issues that developers encounter generate Allows to generate modules for Allegro app bazel Use this command to invoke Bazel with parameters focus Allows to focus on selected modules from Allegro workspace test Runs tests for the given project and scheme Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away OVERVIEW: Steve provides you a convenient way to solve daily 👨💻 development problems and complete repetitive tasks. USAGE: steve <subcommand> OPTIONS: --version Shows the version -h, --help Shows help information SUBCOMMANDS: fixme Fixes most common issues that developers encounter generate Allows to generate modules for Allegro app bazel Use this command to invoke Bazel with parameters focus Allows to focus on selected modules from Allegro workspace test Runs tests for the given project and scheme
6. ./steve generate Networking Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away
7. ./steve generate Networking Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away generates a module based on a template
8. January 2021 78 modules 77 standard modules 1 utility module January 2022 91 standard modules 26 utility modules 117 modules
9. how to inject dependencies to ? 117 modules NetworkClient .shared Core Cart ItemPage Payments SearchEngine Lists … Address OLD import Networking import Networking import Networking import Networking import Networking import Networking import Networking
10. Cart ItemPage Payments SearchEngine Lists … Address Networking 
 Interface Networking NEW import NetworkingInterface import NetworkingInterface import NetworkingInterface import NetworkingInterface import NetworkingInterface import NetworkingInterface how to inject dependencies to ? 117 modules
11. Networking 
 Interface Networking NEW public module private module
12. Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away public & private modules generated based on a new template
13. January 2022 91 private modules 91 public modules 26 utility modules January 2021 78 modules 77 standard modules 1 utility module 208 modules
14. we don’t have in our workspace 208 modules
15. The Build of iOS Conf SG 2021: Speeding up the build process of a monolithic application 208 modules
16. ./steve focus none Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away
17. ./steve focus Cart Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away
18. ./steve focus Networking Cart ItemPage Payments SearchEngine Networking Lists … Address OLD
19. Cart ItemPage Payments SearchEngine Lists … Address Networking 
 Interface Networking ./steve focus Networking NEW Networking 
 Interface
20. Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Cart ItemPage Payments SearchEngine Lists … Address NEW
21. Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Cart ItemPage Payments SearchEngine Lists … Address NEW
22. Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Networking 
 Interface Networking Cart ItemPage Payments SearchEngine Lists … Address NEW
23. Media: https://giphy.com/gifs/nervous-indiana-jones-waiting-oKVs1VY0MKfvO
24. Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9
25. import Networking func injectProductPageDependencies() { let container = ProductPage.DependencyContainer.default container.apiClient = Networking.NetworkClient.shared // … } OLD // Module: Core Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9
26. protocol NetworkingClient { func get(_ resource: Resource) func post(_ resource: Resource) } OLD // Module: Networking
27. protocol NetworkingClient { func get(_ resource: Resource) func post(_ resource: Resource) } // Module: NetworkingInterface NEW
28. import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func registerImplementations(in registry: Registry) { registry.register(type: NetworkingClient.self, service: NetworkClient()) // Module: Networking NEW
29. import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func registerImplementations(in registry: Registry) { registry.register(type: NetworkingClient.self, service: NetworkClient()) } // Module: Networking NEW Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9
30. import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func resolveDependencies(with resolver: Resolver) { guard let networking = resolver.resolve(type: NetworkingClient.self) // Module: ProductPage NEW
31. import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func resolveDependencies(with resolver: Resolver) { guard let networking = resolver.resolve(type: NetworkingClient.self) } } // Module: ProductPage NEW Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9
32. var modules: [ModuleConfiguring.Type] { ProductPage.ModuleConfiguration.self, Networking.ModuleConfiguration.self, / / … } // Module: Application NEW
33. let container: Registry & Resolver = // … modules.forEach { $0.registerImplementations(in: container) } modules.forEach { $0.resolveDependencies(with: container) } // Module: Application NEW
34. // Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { func register<T>(type: T.Type, service: Any) { dependencies[DependencyKey(type)] = service
35. // Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { func register<T>(type: T.Type, service: Any) { dependencies[DependencyKey(type)] = service } }
36. // Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { } func resolve<T>(type: T.Type) -> T? { return dependencies[DependencyKey(type)] as? T }
37. NEW // Summary: New Dependency Injection at scale private public Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Cart ItemPage Payments SearchEngine Lists … Address Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away
38. NEW // Summary: New Dependency Injection at scale private public Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9 func application(_:, didFinishLaunchingWithOptions:) -> Bool { modules.forEach { $0.registerImplementations(in: container) } modules.forEach { $0.resolveDependencies(with: container) } }
39. • lighter workspace • light dependency injection framework • intermodule dependencies on public interfaces • private modules inject implementations of interfaces • module extracts what it needs from the dependencies container // Summary: New Dependency Injection at scale Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9
40. allegro.tech Speeding up iOS builds with Bazel Speeding up warm builds in Xcode Maciej Piotrowski twitter.com/macpiotrowski89 swifting.io
41. https://allegro.tech/2020/12/speeding-up-ios-builds-with-bazel.html https://allegro.tech/2020/12/speeding-up-warm-builds.html https://bazel.build https://github.com/yonaskolb/XcodeGen 
 iOS Conf SG 2021: Speeding up the build process of a monolithic application