UIKit is a lightweight and modular front-end framework.
We have covered Furatto, another front-end framework that is built upon Twitter Bootstrap and the Foundation Frameworks.
UIKit is not built on top of any of the other framework. It is much much lighter than the Twitter Bootstrap and Foundation. It does this without much consequence. You can enjoy UIKit as much as Bootstrap without losing any the awesome components like modal, progress bars, grid framework and navigation buttons.