How to edit code for GUI-constructed nib files?

[nettles]

I'm new to iOS development and working through the Mark/Nutting/LaMarche book.

I am wondering how to open nib files (such as ViewController.xib) in a regular text editor, rather than using the GUI that initially constructs them. I can see and edit the relevant code without difficulty if I open the project's .xcodeproj file in an external editor, but I'm wondering how to do this within Xcode 4 — Xcode always seems to want to open the nib as a graphical interface. Is there a way to open it as editable text?

Thanks for your patient reply.

[edited: found the answer through play:]
It turns out that right-click on the nib file brings up a menu, from which Open As->Source Code gives me what I want.