NSSortDescriptor *sortTitle =[NSSortDescriptor sortDescriptorWithKey:@"addedTimestamp"
                                                               ascending:YES];
    NSArray *sortDescriptors = [NSArray arrayWithObjects:sortTitle, nil];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Expense"
                                              inManagedObjectContext:context];

    NSPredicate *predicate;
    predicate =[NSPredicate predicateWithFormat:@"(addedTimestamp <= %@) AND (addedTimestamp >= %@)",currentDate, endDate];
        NSAttributeDescription* amtDescription = [entity.attributesByName objectForKey:@"amount"];
        NSRelationshipDescription* nameDesc = [entity.relationshipsByName objectForKey:@"expenseCategory"];

        NSExpression *keyPathExpression = [NSExpression expressionForKeyPath: @"amount"];
        NSExpression *countExpression = [NSExpression expressionForFunction: @"sum:"
                                                                  arguments: [NSArray arrayWithObject:keyPathExpression]];
        NSExpressionDescription *expressionDescription = [[NSExpressionDescription alloc] init];
        [expressionDescription setName: @"Sum"];
        [expressionDescription setExpression: countExpression];
        [expressionDescription setExpressionResultType: NSDecimalAttributeType];

        [fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects:amtDescription, expressionDescription, nameDesc, nil]];
        [fetchRequest setPropertiesToGroupBy:[NSArray arrayWithObject:nameDesc]];
        [fetchRequest setResultType:NSDictionaryResultType];

        [fetchRequest setEntity:entity];
        [fetchRequest setPredicate:predicate];
        [fetchRequest setSortDescriptors:sortDescriptors];
    [context executeFetchRequest:fetchRequest error:&error];