Using protocol composition and generics for dependency injection in Interactors (VIPER, SOA, another cool keywords...)

ServicesComposition.swift

protocol HasService1 {
    var service1: Service1 { get }
}
protocol HasService2 {
    var service2: Service2 { get }
}

class Service1 {}
class Service2 {}

//App dependencies
class InteractorDependencies: HasService1, HasService2 {

    lazy var service1: Service1 = {
        return Service1()
    }()
    
    lazy var service2: Service2 = {
        return Service2()
    }()
}

//Base interactor with generic for services
class BaseInteractor<T> {
    
    typealias Dependencies = T
    
    let dependencies: Dependencies
    
    init(dependencies: Dependencies) {
        self.dependencies = dependencies
    }
}

//An example of interactor
class Interactor: BaseInteractor<HasService1 & HasService2> {

    init(viewModel: String, dependencies: Dependencies) {
        super.init(dependencies: dependencies)
    }
}

let interactor = Interactor(viewModel: "cool", dependencies: InteractorDependencies())
interactor.dependencies.service1

//Inspired by: http://merowing.info/2017/04/using-protocol-compositon-for-dependency-injection/