Dependency Injection at scale iOS Conf SG 2022 Maciej Piotrowski | Allegro.pl 

9+ years iOS development Mobile Core Team @ allegro “I make devs’ lives easier” Maciej Piotrowski 

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 

XcodeGen Bazel Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away steve 

OVERVIEW: Steve provides you a convenient way to solve daily 👨💻 development problems and complete repetitive tasks. USAGE: steve 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 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 

./steve generate Networking Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away 

./steve generate Networking Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away generates a module based on a template 

January 2021 78 modules 77 standard modules 1 utility module January 2022 91 standard modules 26 utility modules 117 modules 

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 

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 

Networking 
 Interface Networking NEW public module private module 

Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away public & private modules generated based on a new template 

January 2022 91 private modules 91 public modules 26 utility modules January 2021 78 modules 77 standard modules 1 utility module 208 modules 

we don’t have in our workspace 208 modules 

The Build of iOS Conf SG 2021: Speeding up the build process of a monolithic application 208 modules 

./steve focus none Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away 

./steve focus Cart Media: https://www.macrumors.com/2011/10/05/steve-jobs-has-passed-away 

./steve focus Networking Cart ItemPage Payments SearchEngine Networking Lists … Address OLD 

Cart ItemPage Payments SearchEngine Lists … Address Networking 
 Interface Networking ./steve focus Networking NEW Networking 
 Interface 

Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Cart ItemPage Payments SearchEngine Lists … Address NEW 

Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Cart ItemPage Payments SearchEngine Lists … Address NEW 

Cart 
 Interface ItemPage 
 Interface Payments 
 Interface SearchEngine 
 Interface Lists 
 Interface … Address 
 Interface Networking 
 Interface Networking Cart ItemPage Payments SearchEngine Lists … Address NEW 

Media: https://giphy.com/gifs/nervous-indiana-jones-waiting-oKVs1VY0MKfvO 

Media: https://giphy.com/gifs/cbs-indianajones-harrisonford-raidersofthelostark-TGogvP0s0QESHmyYi9 

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 

protocol NetworkingClient { func get(_ resource: Resource) func post(_ resource: Resource) } OLD // Module: Networking 

protocol NetworkingClient { func get(_ resource: Resource) func post(_ resource: Resource) } // Module: NetworkingInterface NEW 

import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func registerImplementations(in registry: Registry) { registry.register(type: NetworkingClient.self, service: NetworkClient()) // Module: Networking NEW 

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 

import NetworkingInterface class ModuleConfiguration: ModuleConfiguring { func resolveDependencies(with resolver: Resolver) { guard let networking = resolver.resolve(type: NetworkingClient.self) // Module: ProductPage NEW 

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 

var modules: [ModuleConfiguring.Type] { ProductPage.ModuleConfiguration.self, Networking.ModuleConfiguration.self, / / … } // Module: Application NEW 

let container: Registry & Resolver = // … modules.forEach { $0.registerImplementations(in: container) } modules.forEach { $0.resolveDependencies(with: container) } // Module: Application NEW 

// Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { func register(type: T.Type, service: Any) { dependencies[DependencyKey(type)] = service 

// Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { func register(type: T.Type, service: Any) { dependencies[DependencyKey(type)] = service } } 

// Module: DependencyInjection NEW class DependencyContainer: Registry, Resolver { } func resolve(type: T.Type) -> T? { return dependencies[DependencyKey(type)] as? T } 

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 

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) } } 

• 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 

allegro.tech Speeding up iOS builds with Bazel Speeding up warm builds in Xcode Maciej Piotrowski twitter.com/macpiotrowski89 swifting.io 

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