iOS data query love :P...

    NSManagedObject * selectDish = [ self.parentDishController valueForKey:@"selectedDish" ];
 
    NSMutableSet * ingredientsForSelectedDish = [ selectDish valueForKey:@"hasIngredients" ];
    NSSortDescriptor * weightDescriptor = [ [ NSSortDescriptor alloc ] initWithKey:@"weight"
                                                                         ascending:NO ];
    NSArray * ingredientsByWeight = [ ingredientsForSelectedDish sortedArrayUsingDescriptors:
                                        [ NSArray arrayWithObject:weightDescriptor ] ]; 
 
    NSPredicate * ingredientFilter = nil;
 
    ingredientFilter    = omGetFetchedPropertyTemplate( [ self managedObjectModel ], @"Ingredient", @"ingredientsTraces" );
    ingredientsTraces   = [ ingredientsByWeight filteredArrayUsingPredicate:ingredientFilter ];