title: Install Xcode 3.2.4, get "Base SDK Missing"
body: <p>When you update Xcode to 3.2.4, your previously working Xcode iOS project gives you the message "Base SDK Missing". Something like this:</p>
  
  <p><a href="https://i.stack.imgur.com/Y0jIx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Y0jIx.png" alt="Ruh-roh!"></a>
  </p>
  
  <p>What gives? How to fix?</p>