当请求旧数据时，在顶部而不是底部使用fetchedResultsController委托显示tableview的旧消息

Question

Currently I've a Tableview that when it loads it makes a request to Core-Data and grabs the first 10 Messages of the newer ones.

// Initialize Fetch Request
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Chat"];

    // Add Sort Descriptors
    fetchRequest.fetchLimit = 10;
    fetchRequest.predicate = [NSPredicate predicateWithFormat:@"room = %@", _roomid];
    [fetchRequest setSortDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"date_message" ascending:NO]]]; // YES;

    // Initialize Fetched Results Controller
    self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];

    _fetchedResultsController.delegate = self;

    // Perform Fetch
    NSError *error = nil;
    [self.fetchedResultsController performFetch:&error];

    if (error) {
        NSLog(@"Unable to perform fetch.");
        NSLog(@"%@, %@", error, error.localizedDescription);
    }

After I call them. Messages are shown properly under. But When I load (fetch older messages on demand) I use the following.

- (void)fetchOldMessages {

    [self.fetchedResultsController.fetchRequest setSortDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"date_message" ascending:NO]]];
    _fetchedResultsController.fetchRequest.fetchLimit +=10;


    NSError *error = nil;
    [self.fetchedResultsController performFetch:&error];

    if (error) {
        NSLog(@"Unable to perform fetch.");
        NSLog(@"%@, %@", error, error.localizedDescription);
    }

    [self.tableView reloadData];

}

The issue is that the Old messages are now being shown below instead of above the new messages. Also new inserted messages are shown at the top of the tableView instead of the bottom.

this is my IndexPath:

- (UITableViewCell*)tableView:(UITableView*)table cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
                Chat *messageInfo = [self.fetchedResultsController objectAtIndexPath:indexPath];

                NSString *CellIdentifier = @"fromMe";
                FromMeTableViewCell *cell = [table dequeueReusableCellWithIdentifier:CellIdentifier];

                cell.message_me.clipsToBounds = YES;
                cell.message_me.layer.cornerRadius = 15;
                cell.message_me.textContainerInset = UIEdgeInsetsMake(8.0, 8.0, 8.0, 8.0);
                cell.message_me.text = messageInfo.message;
                cell.message_date_me.text = [NSString stringWithFormat:@"%@", messageInfo.date_message];

                cell.avatar_message_me.clipsToBounds = YES;
                cell.avatar_message_me.layer.cornerRadius = cell.avatar_message_me.frame.size.width / 2;
                cell.avatar_message_me.image = user_images[@"me"];
                cell.message_me.backgroundColor = [UIColor colorWithRed:0.098 green:0.737 blue:0.611 alpha:1];
                cell.message_me.textColor = [UIColor whiteColor]; //[UIColor whiteColor];

                // Date Settings
                NSDate *today = [[NSDate alloc]init];
                NSDate *message_date = messageInfo.date_message;

                NSDateFormatter  *formatDate = [[NSDateFormatter alloc]init];
                [formatDate setDateFormat:@"yyyy-MM-dd"];

                NSString *today_string = [formatDate stringFromDate:today];
                NSString *message_date_string = [formatDate stringFromDate:message_date];

                // Make Date validation case is older display full date
                if([today_string isEqualToString:message_date_string]){

                    NSDateFormatter *timeformat = [[NSDateFormatter alloc] init];
                    [timeformat setDateFormat:@"hh:mm a"];

                    NSDate *message_date = messageInfo.date_message;
                    NSString *string_date = [timeformat stringFromDate:message_date];
                    cell.message_date_me.text = [NSString stringWithFormat:@"Today at %@",[NSString stringWithFormat:@"%@",string_date]];

                }
                else {
                    NSDateFormatter *timeformat = [[NSDateFormatter alloc] init];
                    [timeformat setDateFormat:@"EEEE d hh:mm a"];

                    NSDate *message_date = messageInfo.date_message;
                    NSString *string_date = [timeformat stringFromDate:message_date];
                    cell.message_date_me.text = [NSString stringWithFormat:@"%@",[NSString stringWithFormat:@"%@",string_date]];
                }

                return cell;


}

This is when It first loads shows 5 Messages But the last message should be down ant not Above as you can see on the DATE

When I load more Data it shows the Messages in the right Order from new to older but the issue is that I want to show newer messages Below and Older messages Above.

Answer 1

Make your fetch request controller sorting ASCENDING to YES

[self.fetchedResultsController.fetchRequest setSortDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"date_message" ascending:YES]]];