Xcode 4 Interface Builder: How to set File's Owner

Go to the Identity Inspector (Cmd+Option+3) and change the class to myController.

Here it is in 5.1:

I thought I would add this screenshot as it took me some time to find it!

Had the same question... XCode 4.2 enables to create a subclass of UIViewController and there you can optionally check the "with XIB for user interface" option.

New File... >> UIViewControler subclass >> "with xib..."