An AFNetworking . developer designs and implements applications using the AFNetworking . library in iOS. This library is used for networking tasks like sending GET and POST requests, downloading images, and handling JSON, XML, and other responses. The developer manages session tasks, serializes requests and responses, and handles errors. They efficiently use AFNetworking .'s features for managing network reachability, SSL pinning, and network activity indicator, ensuring seamless network operations. They also need to stay updated with the library's changes and improvements, and adjust their code accordingly to maintain app performance and functionality.