title: What are the pitfalls and gotchas of mixing Objective-C and C?
body: <p>At the risk of oversimplifying something I'm worried might be ridiculously complex, what should I be aware of when mixing C and Objective-C? </p>
  
  <p>Edit: Just to clarify, I've never worked with C before, and I'm learning Objective-C through Cocoa. Also I'm using the Chipmunk Dynamics engine, which is C.</p>