title: Xcode throwing "inconsistent number of instance variables specified", but not on newer Mac
body: <p>I'm trying to build some sample code from an Objective-C book I just got. </p>
  
  <p>I'm using an older (2006, 32-bit, Snow Leopard) MacBook Pro with Xcode 4.2. I get about 8 errors about "inconsistent number of instance variables specified". </p>
  
  <p>I compiled the same code on a newer MacBook Pro (2010, 64-bit, Lion) and everything compiles just fine.</p>
  
  <p>Here's a picture with the code and errors expanded:</p>
  
  <p><a href="https://i.stack.imgur.com/mcY23.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mcY23.png" alt=""/></a></p>