Writing Externals for Rev in Xcode

[Kevin]

I'm trying to figure out how to write an external for Revolution. I'm  
familiar with incorporating externals into a Revolution stack and  
calling them from the Revolution side. From the Xcode side, I would  
like to accomplish something very simple, such as the "Hello, <name>!"  
example posted on the RunRev site under "Tutorials":

http://www.runrev.com/developers/tutorials/advanced-externals-part-1/

In this example, the Externals Environment appears to be way out-of- 
date and the sample code will not compile in Xcode. Does anyone have  
any examples or up-to-date articles showing how to integrate Objective- 
C-based externals with Rev?

Cheers,

Kevin