title: How to determine whether class B is a subclass of class A?
body: <p>It seems that if you develop for Mac OS, <code>NSObject</code> has the <code>isSubclassOfClass</code> method. But when I check the iOS class reference for the same class, it does not have the method (and Xcode complains about the method). </p>
  
  <p>My current solutions is to put a method <code>-(void)iAmClassB</code> in there, and perform a <code>respondsToSelector:iAmClassB</code>, but that seems contrived. Am I missing something?</p>