It has a Sketch plugin that does a rather competent job of converting Sketch layers/groups into components. (For example, you can prefix a Sketch group with "c:", and React Studio will interpret it as a component.)
Here is a live video demonstrating the Sketch -> React Studio -> React code workflow: https://www.youtube.com/watch?v=Rfd7zmlFZw8 (It's in realtime with detailed explanations, so it runs about 40 minutes.)
Disclaimer: I wrote a pile of code for React Studio.
