title: Sorting NSMutableDictionary with sortOrder
body: <p>For a sectioned tableView I need to sort my books by category.sortOrder</p>
  
  <pre><code>    NSMutableDictionary *theDictionary = [NSMutableDictionary dictionary];
      for (Book *object in self.books) {            
          NSMutableArray *theMutableArray = [theDictionary objectForKey:object.category.categoryName];
          if ( theMutableArray == nil ) {
              theMutableArray = [NSMutableArray array];
              [theDictionary setObject:theMutableArray forKey:object.category.categoryName];
          }
          [theMutableArray addObject:object];
      }
      self.sections = [[theDictionary allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
  </code></pre>
  
  <p>How can I include the category.sortOrder value in my Dictionary, so I can sort my sections correctly?</p>