Tableview scrolls to top when adding new data. Infinite scroll

Question

When I scroll to the bottom of my tableview and fetch more data with the next offset, i add the new objects to my data array. My tableview however reloads and returns to the first cell. I'm trying to prevent this.

- (void)fetchMovies {
    [MBProgressHUD showHUDAddedTo:self.view animated:YES];

    [self.networkingHelper fetchNowPlayingWithCompletionHandler:^(NSArray *objects, NSError *error) {

     if (error) {
         [self showErrorView:self.errorView];
     } else {
         [self hideErrorView:self.errorView];
     }

     [self.movies addObjectsFromArray:objects];
     self.displayedItems = self.movies;

     dispatch_async(dispatch_get_main_queue(), ^{
         self.isMoreDataLoading = false;

         if ([[NSThread currentThread] isMainThread]){
             NSLog(@"In main thread--completion handler");

             [self.refreshControl endRefreshing];
             [self.loadingMoreView stopAnimating];
             [MBProgressHUD hideHUDForView:self.view animated:YES];
         } else {
             NSLog(@"Not in main thread--completion handler");
         }
         });
       }

     ];
}

Edit Tried adding this

- (void)fetchMovies {
    [MBProgressHUD showHUDAddedTo:self.view animated:YES];

    [self.networkingHelper fetchNowPlayingWithCompletionHandler:^(NSArray *objects, NSError *error)
     {

         if (error)
         {
             [self showErrorView:self.errorView];
         }
         else
         {
             [self hideErrorView:self.errorView];

         }
         [self.movies addObjectsFromArray:objects];
         self.displayedItems = self.movies;


         dispatch_async(dispatch_get_main_queue(), ^{
             self.isMoreDataLoading = false;


             if ([[NSThread currentThread] isMainThread]){
                 NSLog(@"In main thread--completion handler");

                 CGFloat oldOffset = self.moviesTableView.contentSize.height;
                 [self.moviesTableView reloadData];
                 CGFloat onewOffset = self.moviesTableView.contentSize.height;
                 CGPoint new = CGPointMake(0, onewOffset - oldOffset);

                 [self.moviesTableView setContentOffset:new];

                 [self.refreshControl endRefreshing];
                 [self.loadingMoreView stopAnimating];
                 [MBProgressHUD hideHUDForView:self.view animated:YES];


             }
             else{
                 NSLog(@"Not in main thread--completion handler");
             }

             });
     }

     ];
}

Still scrolls to top

I dont think I was clear. I meant my tableview automatically goes to the top cell by itself. I'm trying to prevent this. So a user can continue scrolling through the new entries on the next page — mparrish91, Dec 17 '16 at 04:44
yes to the last cell. when the user swipes down on table and next page is requested. have tableview stay and show next page. — mparrish91, Dec 17 '16 at 04:59
Did you use paging for show your data ? and ya in my answer check your tableview go to your last cell check my updated answer — Himanshu Moradiya, Dec 17 '16 at 05:00
i just got this exception 'NSRangeException', reason: '-[UITableView _contentOffsetForScrollingToRowAtIndexPath:atScrollPosition:]: row (39) beyond bounds (20) for section (0).' — mparrish91, Dec 17 '16 at 05:31
@Dev_Tandel I tried adding that and it allows me to scroll further but still scrolls to top — mparrish91, Dec 17 '16 at 05:42
Yeah I need to play with that more. I got that exception. Seems like i need to time it — mparrish91, Dec 17 '16 at 05:48
@mparrish91 with mine code your tableview scroll goes to bottom of your tableview last cell if you want to give position after some data added then create indexpath as your requirement . — Himanshu Moradiya, Dec 17 '16 at 05:51
@mparrish91 - Then something should be wrong i am using with my 2 chat application and its is working awesome. Lets dig it futhur. — Devang Tandel, Dec 17 '16 at 06:04
@dev_tandel play with the repo? I find that can be easier sometime. Here is link https://github.com/mparrish91/flix — mparrish91, Dec 17 '16 at 06:13

Devang Tandel · Accepted Answer · 2016-12-17T06:50:15.240

1

You are setting

[self.moviesTableView setContentOffset:CGPointMake(0, self.searchController.searchBar.frame.size.height)];

in your addSearchBar method which is being called after load more completed, setting content offset at initial point.

Do also manage you setupInfiniteScrollView Where you are adding subview into Tableview.

And there is little bit changes with the logic

fetch this old y offset position

CGFloat oldOffset = self.moviesTableView.contentOffset.y;

Set the same Y position after load more like

CGPoint new = CGPointMake(0, oldOffset);
 [self.moviesTableView setContentOffset:new];

edited Dec 17 '16 at 06:50

answered Dec 17 '16 at 06:41

Devang Tandel

2,988
1
21
43

i am not getting you – Devang Tandel Dec 17 '16 at 09:18
Thank you this fixed it for me. Dumb error of setting the content offset elsewhere. I did not notice that didLayoutSubviews was called multiple times on table scroll. In layoutSubviews I had awn addSearchBar function. In it i offset my search bar at an initial point. – mparrish91 Dec 20 '16 at 03:09

Himanshu Moradiya · Answer 2 · 2016-12-17T05:00:38.927

Add line in your

if ([[NSThread currentThread] isMainThread]){
        NSLog(@"In main thread--completion handler");

       [self.refreshControl endRefreshing];

       NSIndexPath *indexPath = [NSIndexPath indexPathForRow:[YOURARRAY.count] - 1 inSection:0];
       [self.YOURTABLLENAME scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

       [self.loadingMoreView stopAnimating];
       [MBProgressHUD hideHUDForView:self.view animated:YES];
 }

Eugene Zaychenko · Answer 3 · 2016-12-17T06:05:29.193

0

You need to use dynamic insertion of rows after receiving your data:

NSMutableArray *arrayOfInsertedIndexes = [NSMutableArray array]; 
NSInteger currentCount = self.yourOldData.count; 
for (int i =0; i < yourNewData.count; i++) 
{ 
      [arrayOfInsertedIndexes addObject:[NSIndexPath indexPathForRow:currentCount+i inSection:0]];
}
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:arrayOfInsertedIndexes withRowAnimation:UITableViewRowAnimationRight];
[self.tableView endUpdates];

Do not use

[self.tableView reloadData];

edited Dec 17 '16 at 06:05

answered Dec 17 '16 at 05:55

Eugene Zaychenko

126
8

1

You have update your answer with arrayOfInsertedIndexes value. – Himanshu Moradiya Dec 17 '16 at 05:57
The arrayofinsertedindexes is just the new data not the entire data array? – mparrish91 Dec 17 '16 at 06:00
@mparrish91 take a look. – Eugene Zaychenko Dec 17 '16 at 06:22

Nick Rybalko · Answer 4 · 2016-12-17T06:08:29.423

The problem is that after reloadData contentSize doesn't change synchronous. You should call layoutIfNeeded after reloadData. And only after that contentSize changed

Try this

//.....
 if ([[NSThread currentThread] isMainThread]){
     NSLog(@"In main thread--completion handler");

     CGFloat oldOffset = self.moviesTableView.contentSize.height;
     [self.moviesTableView reloadData];
     [self.moviesTableView layoutIfNeeded];
     CGFloat onewOffset = self.moviesTableView.contentSize.height;
     CGPoint new = CGPointMake(0, onewOffset - oldOffset);

     [self.moviesTableView setContentOffset:new];
     [self.refreshControl endRefreshing];
     [self.loadingMoreView stopAnimating];
     [MBProgressHUD hideHUDForView:self.view animated:YES];
//.......

score 0 · Answer 5 · edited Jul 11 '17 at 01:40

0

Objective C:

 NSIndexPath* ip = [NSIndexPath indexPathForRow:rowNumberHere inSection:sectionNumberHere];
[theTableView scrollToRowAtIndexPath:ip atScrollPosition:UITableViewScrollPositionTop animated:NO];

Swift:

 let offset = CGPoint(x: 0, y: self.tableView.contentSize.height - self.tableView.frame.size.height + self.FOOTERHEIGHT);
 self.tableView.contentOffset = offset;

edited Jul 11 '17 at 01:40

Vinit Ingale

381
1
4
17

answered Dec 17 '16 at 09:05

Aman Gangurde

70
9

Tableview scrolls to top when adding new data. Infinite scroll

5 Answers5