title: NSMakeCollectable and ARC doesn't work
body: <p>I'm trying to convert my old project to ARC. I have a function which creates UUIDs, but apparently this is no longer supported when using ARC:</p>
  
  <pre><code>NSString *uuid = nil;
      CFUUIDRef theUUID = CFUUIDCreate(kCFAllocatorDefault);
      if (theUUID) {
          uuid = NSMakeCollectable(CFUUIDCreateString(kCFAllocatorDefault, theUUID));
          //[uuid autorelease];
          CFRelease(theUUID);
      }
  </code></pre>
  
  <p>I get the compiler error (when trying to convert): 'NSMakeCollectable' is unavailable: not available in automatic reference counting mode.</p>
  
  <p>So my question is: how do I create UUIDs when using ARC? Is there another way which I should now use?</p>