5.4.Plugins/iOS
A limited, simple way to automatically add (as symbolic links) any .a, .m, .mm, .c, or .cpp files into the generated Xcode project. Seehttp://docs.unity3d.com/Documentation/Manual/PluginsForIOS.html
If you need more control how to automatically add files to the Xcode project, you should make use of the PostprocessBuildPlayer feature. Doing so does not require you to place such files in the Plugins/iOS folder. Seehttp://docs.unity3d.com/Documentation/Manual/BuildPlayerPipeline.html