Let's say I'm subclassing `NSString`, for example. My subclass is named `MyString`, and I want to override `[NSString stringWithFormat:]`, but also add another parameter, so my method would be `[MyString stringWithParameter:format:]`. This method would serve to replace `[NSString stringWithFormat:]`. 

If this was my setup, users would still be able to call `[MyString stringWithFormat:]`, which would in turn call `[NSString stringWithFormat:]`. Is there a way to stop users from calling `[MyString stringWithFormat:]`? In other words, is there a way to prevent a subclass of an object from calling particular methods of its parent class?