title: SecItemCopyMatching returns empty dictionary
body: <p>For some reason I got an empty dictionary when calling SecItemCopyMatching on OSX 10.8.4. The corresponding item is in the keychain and contains username and password. SecItemCopyMatching founds it (errSecSuccess) but the result dictionary just contains 0 entries. I would expect it to have at least username and password data, so what's wrong with my request?</p>
  
  <pre><code>OSStatus status;
  NSMutableDictionary *query = [NSMutableDictionary dictionary];
  [query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
  [query setObject:(id)kSecReturnAttributes forKey:(id)kCFBooleanTrue];
  [query setObject:@"MyService" forKey:(id)kSecAttrService];
  
  CFDictionaryRef dictRef = NULL;
  status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&amp;dictRef);
  if (status != errSecSuccess) {
      CFStringRef errorRef = SecCopyErrorMessageString(status, NULL);
      NSLog(@"%s: %@", __FUNCTION__, (__bridge NSString *)errorRef);
      CFRelease(errorRef);
      return nil;
  }
  
  // --&gt; dictRef empty
  
  if (dictRef != NULL) CFRelease(dictRef);
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/3G1Tv.png" alt="enter image description here"></p>