How to call any function after press Enter on IOS Keyboard

Hello.
I need call any setup function after I’m entered any string name in IOS Keyboard field in my app, and then press Enter.
Is any ofxiOSKeyboard method exist for it? Or how I can do it?
Thanks.

ok I’ll make swithсer within isKeyboardShowing() method.
Sorry for inexplicit question. I’m dummy.