SwinjectとProtocol Extensionを用いたDIパターン

DI.swift

@_exported import class Swinject.Container

public struct DIContainer {
    public static let container = Container()
    
    private init() { }
    
    public static func regist(@noescape block: Container -> Void) {
        container.removeAll()
        block(container)
    }
}

protocol UsesCoreComponents {
    var userRepository: UserRepository { get }
}

extension UsesCoreComponents {
    var userRepository: UserRepository {
        return DIContainer.container.resolve(UserRepository.self)! // TODO: Handle errors and logging.
    }
}

regist.swift

DIContainer { container in 
  container.register(UserRepository.self) { _ in UserRepositoryImpl(...) }
            .inObjectScope(.Container)
}

usecase.swift

struct HogeUseCase: UsesCoreComponents {
  func users() -> Future<[User], Error>{
    return userRepository.findAll().map { ... }
  }
}