[vtkusers] Vtk programming on Mac OS X with Xcode

[Jing LI]

Hi Mike, 

Thank you very much for pointing out the right way for me. 

I have built VTK according to the tutorial "Cocoa VTK" on
http://www.vtk.org/Wiki/Cocoa_VTK against Cocoa. And I set
"CMAKE_OSX_ARCHITECTURES:STRING=ppc;i386" too. So I added the
Cocoa.framework to my example vtkcone1. Then in debug mode, I built it, and
ran it without any errors. Thank you very much for the great help. 

Then I changed the mode to release mode, and built it. It gave out errors,
such as 

" Undefined symbols: vtkErrorCode::GetStringFromErrorCode(unsigned long)"

How to fix this problem?

Thank you very much, 

Jing