UITableView , Scroll to bottom on reload?

问题

I have a UITableView with cells that are dynamically updated. Everything works fine apart from when tableview.reload is called (see below) to refresh the cells in the table I would like the table to scroll to the bottom to show the new entries.

- (void)reloadTable:(NSNotification *)notification {
    NSLog(@"RELOAD TABLE ...");
    [customTableView reloadData];
    // Scroll to bottom of UITable here ....
}

I was planning to use scrollToRowAtIndexPath:atScrollPosition:animated: but then noticed that I don't have access to an indexPath.

Does anyone know how to do this, or of a delegate callback that I could use?

回答1:

Use:

NSIndexPath* ipath = [NSIndexPath indexPathForRow: cells_count-1 inSection: sections_count-1];
[tableView scrollToRowAtIndexPath: ipath atScrollPosition: UITableViewScrollPositionTop animated: YES];

Or you can specify the section index manually (If one section => index=0).

回答2:

Another solution is to flip the table vertically, and flip each cell vertically:

Apply the transform to the UITableView when initializing:

tableview.transform = CGAffineTransformMakeScale(1, -1);

and in cellForRowAtIndexPath:

cell.transform = CGAffineTransformMakeScale(1, -1);

This way you don't need workarounds for scrolling issues, but you will need to think a little harder about contentInsets/contentOffsets and header/footer interactions.

回答3:

-(void)scrollToBottom{

        [self.tableView scrollRectToVisible:CGRectMake(0, self.tableView.contentSize.height - self.tableView.bounds.size.height, self.tableView.bounds.size.width, self.tableView.bounds.size.height) animated:YES];

}

回答4:

//In swift 

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

回答5:

This is another solution, worked well in my case, when cell height is big.

- (void)scrollToBottom
{
    CGPoint bottomOffset = CGPointMake(0, _bubbleTable.contentSize.height - _bubbleTable.bounds.size.height);
    if ( bottomOffset.y > 0 ) {
        [_bubbleTable setContentOffset:bottomOffset animated:YES];
    }
}

回答6:

As this is something you might want to use really often, I suggest that you create a class extension on UITableView :

extension UITableView {
    func scrollToBottom(animated: Bool = true) {
        let section = self.numberOfSections
        if section > 0 {
            let row = self.numberOfRowsInSection(section - 1)
            if row > 0 {
                self.scrollToRowAtIndexPath(NSIndexPath(forRow: row - 1, inSection: section - 1), atScrollPosition: .Bottom, animated: animated)
            }
        }
    }
}

回答7:

Swift 3

For all the folks here trying to figure out how to solve this problem the key is to call the .layoutIfNeeded() method after .reloadData() :

tableView.reloadData()
tableView.layoutIfNeeded()
tableView.setContentOffset(CGPoint(x: 0, y: tableView.contentSize.height - tableView.frame.height), animated: false)

I was working with multiple sections in UITableView and it worked well.

回答8:

extension is better to be done on UIScrollView instead of UITableView, this way it works on scrollView, tableView, collectionView (vertical), UIWebView (inner scroll view), etc

public extension UIScrollView {

    public func scrollToBottom(animated animated: Bool) {
        let rect = CGRectMake(0, contentSize.height - bounds.size.height, bounds.size.width, bounds.size.height)
        scrollRectToVisible(rect, animated: animated)
    }

}

回答9:

Fot Swift 5

extension UITableView {
    func scrollToBottom(animated: Bool = true) {
        let section = self.numberOfSections
        if section > 0 {
            let row = self.numberOfRows(inSection: section - 1)
            if row > 0 {

                self.scrollToRow(at: IndexPath(row: row-1, section: section-1), at: .bottom, animated: animated)
            }
        }
    }
}

回答10:

This is the best way.

- (void)scrollToBottom
{
    CGFloat yOffset = 0;

    if (self.tableView.contentSize.height > self.tableView.bounds.size.height) {
        yOffset = self.tableView.contentSize.height - self.tableView.bounds.size.height;
    }

    [self.tableView setContentOffset:CGPointMake(0, yOffset) animated:NO];
}

回答11:

try this code, It may help you:

    self.tableView.reloadData()
    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now()+0.1, execute: {
        let indexPath = IndexPath(row: self.dateSource.count-1, section: 0)
        self.tableView.scrollToRow(at: indexPath, at: UITableViewScrollPosition.bottom, animated: true)
    })

回答12:

Swift 5

    func scrollToBottom() {
        let section = self.tableView.numberOfSections
        let row = self.tableView.numberOfRows(inSection: self.tableView.numberOfSections - 1) - 1;
        guard (section > 0) && (row > 0) else{ // check bounds
            return
        }
        let indexPath = IndexPath(row: row-1, section: section-1)
        self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)
    }

I dont agree that we should user cells_count,sections_count,self.dateSource.countand so on, Instead, the delegate will be better.

来源：https://stackoverflow.com/questions/5112346/uitableview-scroll-to-bottom-on-reload