UIViewController在prepareForSegue上抛出无法识别的选择器异常

I'm trying to follow along the Stanford CS193p iOS programing lectures. One of the demo programs, called "Happiness" creates two UIViewControllers, a "PsychViewController" and a "HappinessViewController." It segues from the PsychViewController to the HappinessViewController using a target action method. I'm trying to follow along the Stanford CS193p