GCC* is the default Xcode* compiler for C, C++, and Objective-C. To use the Intel® C++ Compiler for C or C++ in Xcode, do the following:

• Highlight the target you want to change in the Groups & Files list under the Target group.
• Choose Get Info from the File menu or click the Info button in the toolbar.
• Click Rules in the Target Info window.
• Click the + button at the bottom, left-hand corner of the Target Info window.
• From the Process pull-down menu choose C source files.
• From the using pull-down menu, select Intel® C++ Compiler 10.0.
• Now build the target.

For more informaton please refer to the Compiler User's Guide at /opt/intel/cc/<Compiler Version>/doc/Doc_Index.htm under the section Building Applications » Building Applications with XCode