iOS table view suddenly turns blank

I have some code which brings up a table view in an iPhone app I'm developing. I was attempting to rename the xib file which holds the table display, but after I did it the display table showed up as blank, or rather, with two very large blank lines separated by the normal separators.

My (primitive) backup strategy is to copy the directory folder containing the xcode project. However, when I tried the backup, I get the same result. None of the previous back开发者_如何学Cups before that one work either, until I get to the one before the current enhancement.

Is there something about a project that is preserved by XCode itself, regardless of the directory? What's the best approach to debugging something like this?