For a while I was keenly interested in replacing the underlying text model with my own class, to support some weird stuff I wanted to do. It seemed like it woul

For a while I was keenly interested in replacing the underlying text model with my own class, to support some weird stuff I wanted to do. It seemed like it would be straightforward, given the MVC structure, but the documentation confused me and I never quite figured it out. It didn't seem to be something Apple expected anyone to do.