What is this? An iOS library to do CSS like transformations?

You can easily control transformations with it (out of the box), but it's easily extensible to animate/smooth anything that you can control with a number (think sound, brush strokes in a painting app)

Nice! Can this work with CAAnimation, I would love to use this in Scenekit!

Sure can! You'd add `Animatable` conformance to SCN Types (check out the Animatable.swift file for clear examples) and you'll be all set.

I wonder how stuff like this gets to the front page of HN? Any idea? From the examples, it does not seem to be "physics based" like e.g. box2d.

Here is a physics based animation framework:

https://github.com/kripken/box2d.js/