Limit the number of lines for UITextview

I was wondering how to limit the amount of LINES (not characters as asked in other questions) a user can enter when editing a UITextField.

Ideally, I would like to limit the input to max. 10 lines.

Where would I need to start? Do I do this with a method? In

 - (BOOL)textViewShouldBeginEditing:(UITextView *)aTextView