title: variables declared in @implementation
body: <p>I'm working through a code listing from a book and it has a pair of variables (specifically NSString *) declared and initialised in the @implementation rather than the @interface but outside of any method body. I've not seen this before and I'm wondering what the difference this makes in scope and so on.</p>
  
  <p>I've had a quick look in The Objective C Programming Language but I can't see anything describing what effect this has.</p>
  
  <p>Thanks</p>
  
  <p>Andy</p>