Scrolling to Bottom of UITableView When Messages Load

Question

I'm trying to figure out how to scroll to the bottom of the UITableView once the messages from the database load into it. I've tried using tableView.setContentOffset(CGPointMake(0, CGFloat.max), animated: true) but my table goes from having all the messages in it to nothing at all. I've also tried

var iPath = NSIndexPath(forRow: messagesArray.count - 1, inSection: 0)
tableView.scrollToRowAtIndexPath(iPath, atScrollPosition: UITableViewScrollPosition.Bottom, animated: true)

but I get a EXC_BAD_ACCESS code = 1. Any help would be appreciated.

EDIT:

I'm putting this code in my viewDidAppear() function right after Parse finds the data from the query.findObjectsInBackgroundWithBlock(...), not sure if that makes a difference or not.

Here's the query code:

    query.findObjectsInBackgroundWithBlock { (object, error) -> Void in
                    if (error == nil) {
                        for var i = 0; i < object!.count; i++ {
                            var messageObject = Messages()

                            messageObject.messageID = object![i]["messageID"] as! String

                            println("MESSAGE ID")
                            println(messageObject.messageID)

                            messageObject.messageText = object![i]["message"] as! NSString as String

                            println("MESSAGE TEXT")
                            println(messageObject.messageText)

                            messageObject.recipientID.append(object![i]["recipientID"] as! NSString as String)

                            println("RECIPIENT")
                            println(messageObject.recipientID[0])

                            messageObject.senderID = object![i]["senderID"] as! NSString as String
                            messageObject.timeStamp = object![i]["timeStamp"] as! NSString as String

                            println("TIMESTAMP")
                            println(messageObject.timeStamp)

                            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                                self.messagesArray.append(messageObject)
                            })
                        }


                        self.loadObjects()
                        self.tableView.reloadData()
                        self.tableView.setContentOffset(CGPointMake(0, CGFloat.max), animated: true)
                    }
    }

first check whether the table is loaded in condition fro that indexpath.may be the indexpath is not present — Mukesh, May 15 '15 at 07:04
Where do you get `EXC_BAD_ACCESS code = 1` can you update the log? — Vivek Molkar, May 15 '15 at 07:18
@VivekMolkar I get it on the `tableView.scrollToRowAtIndexPath(...)` line — Navio53, May 15 '15 at 07:41
Put a breakpoint on the second line and print out what `iPath` and `tableView` are - this might give you some clues. — OdieO, May 15 '15 at 07:56
can you put up that portion of code, i mean `query.findObjectsInBackgroundWithBlock(...)` — Vivek Molkar, May 15 '15 at 08:01
Can you call your `self.tableView.reloadData()` and `tableView.scrollToRowAtIndexPath` on main thread? — Vivek Molkar, May 15 '15 at 08:36
@VivekMolkar Wow that made it work! Thanks how did you come up with that? — Navio53, May 15 '15 at 08:48
All UI related task should be performed on main thread. So what you were doing was setting your table view before your datasource getting updated. and we learn from mistakes :-) — Vivek Molkar, May 15 '15 at 09:08

Shruti · Answer 1 · 2015-05-15T07:15:58.867

2

Try This

- (void) viewDidAppear:(BOOL)animated
{
  [super viewDidAppear:animated];
  if (tableView.contentSize.height > tableView.frame.size.height) 
    {
      CGPoint offset = CGPointMake(0, tableView.contentSize.height -tableView.frame.size.height);
      [tableView setContentOffset:offset animated:YES];
   }
}

IN SWIFT

if tableView.contentSize.height > tableView.frame.size.height
    {
        let offset = CGPoint(x: 0, y: tableView.contentSize.height - tableView.frame.size.height)
        tableView.setContentOffset(offset, animated: true)
    }

edited May 15 '15 at 07:15

answered May 15 '15 at 07:13

Shruti

1,849
1
13
21

He requires answer in Swift. – Ashok Londhe May 15 '15 at 07:14
Built in function are also available in Table view for bottom scrolling. Then why should use this kind of logic? – Renish Dadhaniya May 15 '15 at 07:16
I tried this but no luck and I'm putting this code under the call I make to `tableView.reloadData()` – Navio53 May 15 '15 at 07:23

Dharmbir Singh · Answer 2 · 2015-05-15T08:10:20.700

Please try this one

In Objective-c

 NSInteger bottomRow = [self.dataArr count] - 1; // this is your count's array.
    if (bottomRow >= 0) {
        NSIndexPath *indexPath = [NSIndexPath indexPathForRow:bottomRow inSection:0];
        [self.tblview scrollToRowAtIndexPath:indexPath
                               atScrollPosition:UITableViewScrollPositionTop animated:animated];
    }

in swift

var bottomRow : NSInteger = dataArr.count-1;
if (bottomRow >= 0) {

            var indexPath : NSIndexPath = NSIndexPath(forRow: bottomRow, inSection: 0)


            tblview.scrollToRowAtIndexPath(indexPath, atScrollPosition: UITableViewScrollPosition.Bottom, animated: true)

        }

Have you connected your IBOutlet with tableview? – Dharmbir Singh May 15 '15 at 08:10 — Dharmbir Singh, May 15 '15 at 08:10

score 2 · Answer 3 · answered Feb 13 '17 at 10:50

2

I called below method and it worked for me. But, make sure to call it before reloading your tableview.

[tableView setContentOffset:CGPointMake(0, CGFLOAT_MAX)]; 
[tableView reloadData];

Hope it will help you.

answered Feb 13 '17 at 10:50

neena-systematix

61
4

score 0 · Answer 4 · answered May 15 '15 at 08:19

When you table get loaded then scroll it after few time.

- (void)viewDidApear{
 //Please convert it into swift.
   [self performSelector:@selector(scrollToBottom:) withObject:nil afterDelay:0.5];
}

- (void)scrollToBottom:(id)sender{

// Scroll to bottom here

    var iPath = NSIndexPath(forRow: messagesArray.count - 1, inSection: 0)
tableView.scrollToRowAtIndexPath(iPath, atScrollPosition: UITableViewScrollPosition.Bottom, animated: true)
}

Scrolling to Bottom of UITableView When Messages Load

4 Answers4