Well, it's not exactly true that you can live completely without a nib file; getting the main menu to work correctly is harder than it, well, ought to be, and NSApplicationMain() loads a nib by default. Jeff Johnson did a series on Working without a nib, and it's worth adding that (at least for now), NSApplicationMain() is still about equivalent to the following code (according to the NSApplication docs):

[NSApplication sharedApplication]; [NSBundle loadNibNamed: [[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSMainNibFile"] owner:NSApp]; [NSApp run];

Of course, you could always use a minimal MainMenu.nib and create the rest of your interface in code, avoiding the need for the few secret overrides Jeff discovers.