Systems, methods, apparatuses, and software for touch input systems in computing environments are provided herein. In one example, an interaction service positioned logically between an operating system and an application is provided. The interaction service directs a processing system to receive a call from the application referencing an interaction class to attach to an object in a user interface used for the application, wherein the interaction class comprises a set of declarative statements. The interaction class attaches to the object in the user interface. A user input is then identified to the operating system associated with the object. In response to the user input, the interaction service determines which one of the declarative statements corresponds to the user input. The one of the declarative statements is then executed to call corresponding native code that performs an action with respect to the object.