How does Xcode know who the project was "created by"?

In Address Book select yourself (or add yourself if you aren't there) and then go to Card -> Make This My Card in menu bar. The name, last name and company name from that card will be used to populate info in file headers when creating files from Xcode templates.

Alternatively, you could set it using defaults via Terminal.app like this:

defaults write com.apple.Xcode PBXCustomTemplateMacroDefinitions '{ORGANIZATIONNAME="ACME Inc.";}'

System Preferences --> Users & Groups --> choose Current User --> right click Current User --> Advanced Options --> change the full name It works in Xcode 6.3.2

The template comes from i.e. /Developer/Platforms/iPhoneOS.platform/Developer/Library/Xcode/Templates/File Templates/Cocoa Touch/Objective-C class.xctemplate/NSObject/FILEBASENAME.h

You can harcode some custom info(like code warranty or other legal text). Play with it to achieve desired results, but this is the hard and clumsy way

On the easy way useful hint would be that you can change Organization property on the Utilities pane(right side) in Xcode4, when editing the project file(liek build settings). It will be applied to all files created in this project.

It uses you own information from the address book.

Got to:

System Preferences --> Users & Groups --> choose current User --> and press Open at Address Book Card.

There you will find you own information used in xcode.