解析SignUpViewController signUpViewControllerShouldSignBeginSignUp委托函数未被调用

I am writing a Parse app and using the Parse LoginViewController and SignUpViewController. I have been using the SubclassConfigViewController as a model from their LoginAndSignUp demo. As they talk about in their documentation, I want to check the username and password for various things before the signUp commences. This should take place in the delegate function "signUpViewControllerShouldSignBeginSignUp"I am writing a Parse app and using the Parse Lo