Resources...

Airspy SDR  produce various SDR radios and their own software package 'SDR#' Their software also supports RTL-SDR radios 

SDRplay  have a line of excellent line SDR receivers that come with a great software package for their radios call SDRuno.

RTl-SDR.com  is a blog style website with an extremely comprehensive catalogue of everything SDR related from software, hardware and everything in between.

NANA API is a c++ cross platform library containing many great helpers including graphic and math libraries. It is also used by the SDRplay plugin API.

This is a link to my public projects on GitHub.  You can also find my free C# wrapper and library for the Contour Shuttle line of devices.