The popularity of mobile application platforms like IOS, Android or Windows Phone 7 increases from day to day. Affiliated app stores offer thousands of different applications (so called apps) for nearly any imaginable purpose. From a software developer's point of view these app stores provide high potential: developers have the chance to reach the general public, thus having a much broader audience than with any other channel of distribution. Nevertheless, the increased amount of potential customers also increases expectations related to user experience. The user interface as the main interaction hub in mobile environments attracts a lot more attention. The success or failure of an app is often related to its user interface. Furthermore, users often demand the same user experience on different platforms. In order to allow for high quality in user interface development and to enable development for different platforms, a framework is presented that provides a platform independent definition of a user interface backed by constraints in form of rules. Using model driven development, the framework allows the creation of user interfaces that are not related to a specific target technology. Furthermore, it provides the ability to define a user interface and transform it into a destination user interface, whether this will be Android, iPhone or Windows Phone 7, with respect to given rules.