UITableView滚动到底部

Question

我有这行代码:

tableView.contentOffset = CGPointMake(0.0f, 10000000.0f);

内容大小远小于10000000.0f,但UITableView仍然不会滚动到底部.我该怎么做？

Answer 1

滚动到tableViewCell？

//for instance, you have 15 cells
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:14 inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPath
                      atScrollPosition:UITableViewScrollPositionTop
                              animated:YES];

Answer 2

您可以创建 的扩展UIScrollView，并将其用于 UIScrollView、UITableView 或 UICollectionView 的任何实例。

extension UIScrollView {

    func scrollToBottom(animated: Bool) {
        var y: CGFloat = 0.0
        let HEIGHT = self.frame.size.height
        if self.contentSize.height > HEIGHT {
            y = self.contentSize.height - HEIGHT
        }
        self.setContentOffset(CGPointMake(0, y), animated: animated)
    }
}

每当内容大小大于滚动视图的高度时，它将相应地滚动到正确的位置。此方法也适用于 AutoLayout。

Answer 3

Swift 5，iOS 12 测试

这段代码非常适用于UITableView，即使有 0 个元素的部分（这会在我在互联网上看到的所有其他解决方案中崩溃）

extension UITableView {
    func scrollTableViewToBottom(animated: Bool) {
        guard let dataSource = dataSource else { return }

        var lastSectionWithAtLeasOneElements = (dataSource.numberOfSections?(in: self) ?? 1) - 1

        while dataSource.tableView(self, numberOfRowsInSection: lastSectionWithAtLeasOneElements) < 1 {
            lastSectionWithAtLeasOneElements -= 1
        }

        let lastRow = dataSource.tableView(self, numberOfRowsInSection: lastSectionWithAtLeasOneElements) - 1

        guard lastSectionWithAtLeasOneElements > -1 && lastRow > -1 else { return }

        let bottomIndex = IndexPath(item: lastRow, section: lastSectionWithAtLeasOneElements)
        scrollToRow(at: bottomIndex, at: .bottom, animated: animated)
    }
}

本主题中 Kevin 的固定版本，防止带有0项目的tableView 无限滚动： 来源：https : //stackoverflow.com/a/59470799/9763761

func scrollToBottom(animated: Bool) {
    guard let dataSource = dataSource else { return }
    var lastSectionWithAtLeastOneElement = (dataSource.numberOfSections?(in: self) ?? 1) - 1
    while dataSource.tableView(self, numberOfRowsInSection: lastSectionWithAtLeastOneElement) < 1 && lastSectionWithAtLeastOneElement > 0 {
        lastSectionWithAtLeastOneElement -= 1
    }
    let lastRow = dataSource.tableView(self, numberOfRowsInSection: lastSectionWithAtLeastOneElement) - 1
    guard lastSectionWithAtLeastOneElement > -1 && lastRow > -1 else { return }
    let bottomIndex = IndexPath(item: lastRow, section: lastSectionWithAtLeastOneElement)
    scrollToRow(at: bottomIndex, at: .bottom, animated: animated)
}

此代码适用于UIScrollView，但不适用于UITableView单元数多于一个屏幕可以容纳的单元格，因为 Apple 奇怪的内部实现UITableViewController：

extension UIScrollView {
    func scrollToBottom(animated: Bool) {
        guard contentSize.height > bounds.size.height else { return }

        let bottomOffset = CGPoint(x: 0, y: contentSize.height - bounds.size.height + contentInset.bottom)
        setContentOffset(bottomOffset, animated: true)
    }
}