Setting scroll position in UITableView

Question

I have an application that works some what similar to how iPhone's Contact application works. When we add a new Contact user is directed to a view only screen with Contact information. If we select "All Contacts" from the navigation bar, user is navigated to list of all contacts where the recently added contact is in view.

We can move the view to a particular row using:

    [itemsTableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionBottom];

... but it's not working. I'm calling this right after calling:

    [tableView reloadData];

I think I'm not suppose to call selectRowAtIndexPath:animated:scrollPosition method here. But if not here, then where?

Is there any delegate method that gets called after the following method?

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;

Answer 1

I think I've got a similar app: A list of item., tap '+' -> new screen, come back and see the updated list, scrolled to show the added item at the bottom.

In summary, I put reloadData in viewWillAppear:animated: and scrollToRowAtIndexPath:... in viewDidAppear:animated:.

// Note: Member variables dataHasChanged and scrollToLast have been
// set to YES somewhere else, e.g. when tapping 'Save' in the new-item view.

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    if (dataHasChanged) {
        self.dataHasChanged = NO;
        [[self tableView] reloadData];
    } else {
        self.scrollToLast = NO; // No reload -> no need to scroll!
    }
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    if (scrollToLast) {
        NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:([dataController count] - 1) inSection:0];
        [[self tableView] scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
    }
}

I hope this helps. If you add something in the middle of the list, you could easily scroll to that position instead.

Answer 2

You can try this , my application in some kind of similar to you when i click on a button scroll of uitableview is up.

[tableviewname setContentOffset:CGPointMake(0, ([arrayofcontact count]-10)*cellheight) animated:YES];

10 is for how many cell you want to scroll up

Hope this will help you:-)

Answer 3

Scrolling animation is inevitable when offset is set from viewDidAppear(_:). A better place for setting initial scroll offset is viewWillAppear(_:). You'll need to force the layout of a table view, because it's content size is not defined at that point.

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    tableView.setNeedsLayout()
    tableView.layoutIfNeeded()

    if let selectedIndexPath = selectedIndexPath, tableView.numberOfRows(inSection: selectedIndexPath.section) > 0 {
        tableView.scrollToRow(at: selectedIndexPath, at: .top, animated: false)
    }
}

Answer 4

Do you have enough dummy contacts added to test the scrolling? It seems that only when your tableView is of a certain size the iPhone finds the inputus to scroll.

This is the code that works for me in my project. I use a previous button and therefore I scroll the tableview a little bit further down that it usually would go with UITABLEVIEWSCROLLPOSITION. (my previous button won't work if it can't "see" the previous cell.

Ignore some of the custom method calls.

- (void)textFieldDidBeginEditing:(UITextField *)textField {

    //Show the navButtons
    [self navButtonAnimation];


    DetailsStandardCell *cell = (DetailsStandardCell *)textField.superview.superview.superview;

    self.parentController.lastCell = cell;


    //Code to scroll the tableview to the previous indexpath so the previous button will work. NOTE previous button only works if its target table cell is visible.
    NSUInteger row = cell.cellPath.row;
    NSUInteger section = cell.cellPath.section;

    NSIndexPath *previousIndexPath = nil;


    if (cell.cellPath.row == 0 && cell.cellPath.section != 0) //take selection back to last row of previous section
    {
    NSUInteger previousIndex[] = {section -1, ([[self.sections objectForKey:[NSNumber numberWithInt:section - 1]]count] -1)};
    previousIndexPath = [[NSIndexPath alloc] initWithIndexes:previousIndex length:2];   
    }
    else if (cell.cellPath.row != 0 && cell.cellPath.section != 0)
    {
        NSUInteger previousIndex[] = {section, row - 1};
        previousIndexPath = [[NSIndexPath alloc] initWithIndexes:previousIndex length:2];       

    }


    [self.theTableView scrollToRowAtIndexPath: cell.cellPath.section == 0 ? cell.cellPath : previousIndexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];

}