At first, I make a connection from button event (touch up inside) to file owner of view controller and select a function for that event. The function works fine. Then, I would like to change the function name for that event. I delete the link of that event and make a new connection with the new function. I clean and build the whole application. When running the new application, the touch up inside event simply does not work and everything else works. Can anyone tells me which steps should I do to clean up the environment and make the button work again?