This sample shows how to issue http/https web requests using .NET and Objective-C API. Main actions takes place in NetworkHandlers.cs file. There you will find Cocoa and DotNet classes. DotNet class uses standard WebRequest to create web-requests. On the other hand Cocoa utilizes NSUrlRequest native class.
OS X 10.10, Xcode 6.0 or later
OS X 10.10
Checkout how to issue http/https web requests in Xamarin.iOS here