Xcode debug and release build config.

It depends of the config settings, but in general release should be smaller than debug.
For doc XCode>Help>XcodeHelp gives one a list of manuals in HTML and PDF formats.

Jeffrey Young wrote:
Why is the release version of the active executable about twice the size of the debug version?

It depends. What kind of code is it? C++ code with lots of templates could get big. Static linking could cause it too.

Does Apple have a PDF manual for Xcode?

No, they have about 3271 PDF manuals for Xcode. Which one do you want? Usually there is a little "PDF" button on the toolbar of the document you are looking at.

The release version is twice the size of the debug version because Xcode builds universal binaries in the release version and builds only for your architecture in the debug version. When you build the release version, you have at least two copies of your executable: Intel and PowerPC. When you build the debug version, there's only one copy of the executable.

Good point, I jumped to the conclusion that the IP was referring to an iphone app.