How to populate UITableView from the bottom upwards?

Here is a refined solution of KlimczakM´s solution that works with autolayouted tableview cells (as well as the fixed ones). This solution also works with sections, section headers and section footers.

Swift 3.0:

func updateTableContentInset(forTableView tv: UITableView) {
    let numSections = tv.numberOfSections
    var contentInsetTop = tv.bounds.size.height -
        (self.navigationBar?.frame.size.height ?? 0)

    for section in 0..<numSections {
        let numRows = tv.numberOfRows(inSection: section)
        let sectionHeaderHeight = tv.rectForHeader(inSection: section).size.height
        let sectionFooterHeight = tv.rectForFooter(inSection: section).size.height
        contentInsetTop -= sectionHeaderHeight + sectionFooterHeight
        for i in 0..<numRows {
            let rowHeight = tv.rectForRow(at: IndexPath(item: i, section: section)).size.height
            contentInsetTop -= rowHeight
            if contentInsetTop <= 0 {
                contentInsetTop = 0
                break
            }
        }
        // Break outer loop as well if contentInsetTop == 0
        if contentInsetTop == 0 {
            break
        }
    }
    tv.contentInset = UIEdgeInsetsMake(contentInsetTop, 0, 0, 0)
}

NOTE:

Above code is untested but should work. Just make sure that you cope for the height of any navbar or tabbar and you'll be fine. In the code above i only do that for the navbar!

Swift 4.0 and 4.2 version

First reverse UITableView in viewDidLoad

override func viewDidLoad() {
        super.viewDidLoad()
        tableView.transform = CGAffineTransform(scaleX: 1, y: -1)
}

Then reverse the cell in cellForRowAt.

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "MyTableViewCell", for: indexPath) as? MyTableViewCell else { fatalError() }

        cell.contentView.transform = CGAffineTransform(scaleX: 1, y: -1)
        return cell
    }

first reverse uitableview

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

then reverse cell in cell create.

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

    ...

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

To populate UITableView from the bottom:

- (void)updateTableContentInset {
    NSInteger numRows = [self.tableView numberOfRowsInSection:0];
    CGFloat contentInsetTop = self.tableView.bounds.size.height;
    for (NSInteger i = 0; i < numRows; i++) {
        contentInsetTop -= [self tableView:self.tableView heightForRowAtIndexPath:[NSIndexPath indexPathForItem:i inSection:0]];
        if (contentInsetTop <= 0) {
            contentInsetTop = 0;
            break;
        }
    }
    self.tableView.contentInset = UIEdgeInsetsMake(contentInsetTop, 0, 0, 0);
}

To reverse the order of elements:

dataSourceArray = dataSourceArray.reverseObjectEnumerator.allObjects;

Swift 4.2/5 version:

func updateTableContentInset() {
    let numRows = self.tableView.numberOfRows(inSection: 0)
    var contentInsetTop = self.tableView.bounds.size.height
    for i in 0..<numRows {
        let rowRect = self.tableView.rectForRow(at: IndexPath(item: i, section: 0))
        contentInsetTop -= rowRect.size.height
        if contentInsetTop <= 0 {
            contentInsetTop = 0
            break
        }
    }
    self.tableView.contentInset = UIEdgeInsets(top: contentInsetTop,left: 0,bottom: 0,right: 0)
}

Swift 3/4.0 version:

self.tableView.contentInset = UIEdgeInsetsMake(contentInsetTop, 0, 0, 0)