Core Data w/out Document based


Dear Sirs,

i would like to make an App using Core data, but without option of Document based.I want to have only one instance of the model.
The window to loads as soon as the app starts and automatically to save the data (not to ask user where to save the file).
My question is: Why when creating basic Cocoa App XCode generates my_app_nameAppDelegate file and sometimes XCode don’t.In the example in the book it didn’t create AppDelegate.