Silk is a thin layer on top of NSURLSession. While it may not be as sophisticated as a full featured HTTP library such as AFNetworking, it does a good job of abstracting the most commonly used functions when talking to an app backend server. Silk is very lightweight and does not bloat your project with unneccesary stuff.
Use CocoaPods to add Silk to your project. Just add the following line to your Podfile.
pod 'Silk', '~> 3.1.0'