AE SDK plugin project setup in XCode

I need to port some AE effects plugins to OSX and I have never used XCode before. Unsurprisingly,Adobe supplied no demo of project setup.Should it be a "bundle" or  "C/C++ plugin"  , or anything else?Not a single line on it.

I opened the example projects from the SDK.I see that the target files ,all of them have the ending ".plugin" and build properties which I can't find when creating custom builds.I am using XCode 4.5 .Anyone can explain the main steps to confgure plugins just like the SDK examples?

Thanks.