Note: Although you can create an Objective-C application without using nib files, doing so is very rare and not recommended. Depending on your application, avoiding the use of nib files can involve overriding large amounts of framework behavior to achieve the same results you would get using a nib file.I don't think Apple could be much clearer on this point. Apple and NeXT developers have been using Interface Builder for twenty-one years, longer than many programmers have been programming. I think, at this point, they've got a pretty good handle on how it works and when it should be used. It boggles my mind that there's even a debate on this issue. There's really no excuse for creating your user interface in code in the vast majority of situations. Using Interface Builder is faster and much easier to maintain.
Don't fight the design, work with it.
Thanks to Saurabh Garg for pointing this out.