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。我该怎么办？

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UITableView的扩展名，并在必要时将其用作常规表格视图方法。

extension UITableView {

    let SCREEN_HEIGHT = UIScreen.mainScreen().bounds.height

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

每当内容大小超过屏幕高度时，它将相应地滚动到正确的位置。此方法也适用于AutoLayout。

Answer 3

试试这段代码：

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)
})

Answer 4

Swift 5，iOS 12已测试

?即使某些节中的元素为0（即使我在Internet上看到的所有其他解决方案都将崩溃），此代码也适用于UITableView。

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)
    }
}

?此代码适用于UIScrollView，但不适用于UITableView且其单元格多于一个屏幕可以容纳的空间，原因是苹果公司内部对UITableViewController进行了怪异的内部实现：

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)
    }
}

Answer 5

不幸的是，我没有足够的代表对此发表评论，但是vol的答案有1个错误，当您在具有0个项目的表视图上调用它时，它会导致无限的while循环，此外它还能正常工作！更正了以下代码：

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)
}