DIY DI

The grown up languages use dependency injection all the time. This talk takes a look at a problem I was experiencing in an iOS app, and then a quick run through a potential (evolving) solution.

Transcript

1. DIY DI sam : @iwantmyrealname github.com/sammyd/iOSCon2018_DIYDI
2. single tons
3. single tons
4. one instance
5. network controller
6. file access
7. animation engine
8. what's the problem?
9. global access
10. class Manager { static let shared = Manager() private init() }
11. class Manager { static let shared = Manager() private init() } let manager = Manager.shared
12. bad
13. hidden state
14. hard to test
15. possible solution...
16. don't allow global access
17. give objects what they need
18. inject their dependencies
19. hierarchy problem
26. alternative
27. a way to find dependencies
29. contained facsimile for global state
30. dependency container
31. protocol NetworkManagerProvider { var networkManager: NetworkManager { get } }
32. protocol NetworkManagerProvider { var networkManager: NetworkManager { get } } protocol DataStoreProvider { var dataStore: DataStore { get } }
33. protocol NetworkManagerProvider { var networkManager: NetworkManager { get } } protocol DataStoreProvider { var dataStore: DataStore { get } } protocol ViewControllerFactory { func createBeautifulVC() -> UIViewController ... }
34. class DependencyContainer: NetworkProvider, DataStoreProvider, ViewControllerFactory { ... }
35. class MyViewController { typealias DependencyProvider = NetworkManagerProvider & ViewControllerFactory ... }
36. class MyViewController { typealias DependencyProvider = NetworkManagerProvider & ViewControllerFactory private let provider: DependencyProvider ... }
37. class MyViewController { typealias DependencyProvider = NetworkManagerProvider & ViewControllerFactory private let provider: DependencyProvider private lazy var dataStore = provider.dataStore ... }
38. class MyViewController { typealias DependencyProvider = NetworkManagerProvider & ViewControllerFactory private let provider: DependencyProvider private lazy var dataStore = provider.dataStore init(dependencyProvider: DependencyProvider) { self.dependencyProvider = dependencyProvider } }
39. by no means perfect
40. but better than before
41. DI/IoC popular with the grownups
42. consider it when you're struggling
43. @iwantmyrealname github.com/sammyd/iOSCon2018_DIYDI