objective c - Cocoa move to parent from a subclassed instance -

I have a subclassed NSTextField to limit the maximum length (1 character only). Now, once the user enters this character, I want to take Focus to the next NSTTXTV. This is the place where I need some help. How can I apply the application "Take the focus to the next field"? I think I need to call the original view from the subclassed NSTextField, like something:

  [[parent] next KYV];  

But how do I do this?