Discrepancy between tutorial on developer.apple.com and Xcode project template

I was following the tutorial at developer.apple.com for learning Cocoa, and I found something in my project that was not in the tutorial. It was the Application Delegate that was made when I started the project. In their tutorial it shows this in interface builder:

The file I have on my Mac, opened in Interface Builder, looks like this:

Also, I cannot add the Controller class to my xib file. It gives me the error:

Parsed 1 source file, but no classes were found or changed.

Is the tutorial old or am I doing something wrong? And what is the App Delegate class?

The tutorial is old, but to answer your question, the App Delegate is an NSObject that implements the NSApplicationDelegate protocol. More infor here.

You don't necessary need to do anything with this class with respect to your tutorial. As you write more advanced programs you will find that the application delegate can be very useful.