title: How can I find out which Cocoa classes and APIs are portable across MacOSX and IOS?
body: <p>There are a number of useful business logic classes which seem to exist in both iOS and MacOSX (for example, <code>NSMutableDictionary</code>). </p>
  
  <p>However as far as I can see the developer documentation does not indicate which they are - you're either using the Mac developer docs (in which case it will tell which version of OSX the API appeared in), or the iOS docs (in which case ditto for iOS).</p>
  
  <p>Is there any documentation set (or alternative easy way) to find out which classes exist in both - i.e. the equivalent of "Available in iOS since version foo, OSX since version bar"?</p>