APIServices.swift

class API {
    let service: NetworkService
    
    init(_ service: NetworkService = URLSession.shared) {
        self.service = service
    }
    
    func send(request: URLRequest, completionHandler: @escaping CompletionBlock) {
        service.make(request: request, completionHandler: completionHandler)
    }
}

class HomeViewController() {
    
    func testServices() {
        let service0 = API(URLSession.shared)
        let service1 = API(PilotService())
        let service2 = API(TestService())
        let service3 = API(MockedService())
        let request = URLRequest(url: URL(string: "https://google.com")!)

        service0.send(request: request) { data in
            print(data!)
        }

        service1.send(request: request) { data in
            print(data!)
        }

        service2.send(request: request) { data in
            print(data!)
        }
        
        service3.send(request: request) { data in
            print(data!)
        }
    }    
}