I wrote a simple DH and SmartApp for Ikea Sonos Controller, code and documentation can be found from here: https://github.com/jusa80/smartthings . To get it working you just need to install the DH and pair the Controller with four pushes.
I am using HUB v3 and new Smartthings App. With old App the UI for the device looks fine but I would like to make UI also prettier on new App. From where I could find some examples about DH UI for new App?