unity object representation

can any body tell me how objects are represented in Unity ?

ex: i imported .3ds file into unity, so how these objects internally represented in unity?

If you want to access or alter the model in code, have a look at the Mesh class.

Maybe this is in fact how the mesh objects are represented internally in memory, but it might just be an interface that hides the true internal representation. I don't believe anyone outside of Unity Technologies knows for sure, and I doubt it matters to anyone else. (For all we know it could be different depending on what platform the player is running on, in order to more efficiently pass data to DirectX or OpenGL.)

so what about passing unity project code to xcode in order to build the project

in that case where is the resource files that xcode reads graphics scene from ?