以下是我在iOS 11上正确运行的方法:

extension UIScrollView {
    func scrollToTop(animated: Bool) {
        var offset = contentOffset
        if #available(iOS 11, *) {
            offset.y = -adjustedContentInset.top
        } else {
            offset.y = -contentInset.top
        }
        setContentOffset(offset, animated: animated)
    }
}

在Swift 5中，非常感谢@Adrian的回答

extension UITableView{

    func hasRowAtIndexPath(indexPath: IndexPath) -> Bool {
        return indexPath.section < numberOfSections && indexPath.row < numberOfRows(inSection: indexPath.section)
    }

    func scrollToTop(_ animated: Bool = false) {
        let indexPath = IndexPath(row: 0, section: 0)
        if hasRowAtIndexPath(indexPath: indexPath) {
            scrollToRow(at: indexPath, at: .top, animated: animated)
        }
    }

}

用法:

tableView.scrollToTop()

func scrollToTop() {
        NSIndexPath *topItem = [NSIndexPath indexPathForItem:0 inSection:0];
        [tableView scrollToRowAtIndexPath:topItem atScrollPosition:UITableViewScrollPositionTop animated:YES];
}

调用这个函数，无论你想让UITableView滚动到顶部

斯威夫特4:

这个方法非常有效:

//self.tableView.reloadData() if you want to use this line remember to put it before 
let indexPath = IndexPath(row: 0, section: 0)
self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)

UITableView是UIScrollView的子类，所以你也可以使用:

[mainTableView scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:YES];

Or

[mainTableView setContentOffset:CGPointZero animated:YES];

在Swift中:

mainTableView.setContentOffset(CGPointZero, animated:true)

在Swift 3及以上版本中:

mainTableView.setContentOffset(.zero, animated: true)

迅速:

tableView.setContentOffset(CGPointZero, animated: true)