newSiteConfig.values().removeObjectForKey("password");
// Build a dictionary of new values. Because we might only be updating a few values (and not the whole
// SiteConfig) we'll start with all the current values, less the password which we've already cached.
NSMutableDictionary newValues = siteConfig().values();
newValues.removeObjectForKey("password");
// Overwrite and/or add the new incoming values.
newValues.addEntriesFromDictionary(newSiteConfig.values());
// Push the complete set of new values into the current SiteConfig object.