Method swizzling should work as kidnamedlox suggested .
Your exact same question was discussed in this stanfordStanford itunes class by Evan Doll
http://deimos3.apple.com/WebObjects/Core.woa/Browse/itunes.stanford.edu.2024353965.02024353968.2173787533?i=1949208242https://podcasts.apple.com/us/podcast/iphone-application-programming-spring-2009/id384233222