KDE has today made the first update to KDE Frameworks 5. Frameworks are our addon libraries for Qt applications which provide numerous useful features using peer reviewed APIs and regular monthly updates. This release has 60 different Frameworks, adding features from Zip file support to Audio file previews. For a full list, see KDE's Qt library archive website Inqlude. In this release KAuth gets a backend so you can again add features which require root access, KWallet gets a migration system from its KDELibs 4 version, and support has been added for AppStream files.
To code with Frameworks, read the API documentation and install them with Linux distro binary packages or grab the source code directly.