Network Framework with Native Session Manager and different third parties support

I am creating a Networking framework which should supports native NSURLSessionManager and can adopt any third party also (Ex - Alamofire and AFNetworking) to fetch data.

Application layer will pass request to my Network manager and can instruct whether data is to be fetched from Alamofire manager or native session manager.

How can I achieve this without adding any third party code in my framework. If in future any application wants to use any other third party library that could also be supported.

Any help is appreciable.