Question

如何检测UITableView何时滚动到底部以便最后一个单元格可见？

Answer 1

内部tableView:cellForRowAtIndexPath:或tableView:willDisplayCell:forRowAtIndexPath:，如下所示：

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

    ...

    NSInteger sectionsAmount = [tableView numberOfSections];
    NSInteger rowsAmount = [tableView numberOfRowsInSection:[indexPath section]];
    if ([indexPath section] == sectionsAmount - 1 && [indexPath row] == rowsAmount - 1) {
        // This is the last cell in the table
    }

    ...

}

Answer 2

在UITableViewDelegate中实现tableView:willDisplayCell:forRowAtIndexPath:方法并检查它是否是最后一行。

Answer 3

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    NSInteger lastSectionIndex = [tableView numberOfSections] - 1;
    NSInteger lastRowIndex = [tableView numberOfRowsInSection:lastSectionIndex] - 1;
    if ((indexPath.section == lastSectionIndex) && (indexPath.row == lastRowIndex)) {
        // This is the last cell
    }
}

Answer 4

为UITableView创建优雅的扩展程序：

extension UITableView {

    func isLast(for indexPath: IndexPath) -> Bool {

        let indexOfLastSection = numberOfSections > 0 ? numberOfSections - 1 : 0
        let indexOfLastRowInLastSection = numberOfRows(inSection: indexOfLastSection) - 1

        return indexPath.section == indexOfLastSection && indexPath.row == indexOfLastRowInLastSection
    }
}

使用示例：

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    if tableView.isLast(for: indexPath) {
        //do anything then
    }

    return cell
}

Answer 5

对于Xcode 9和Swift 4/5

//Show Last Cell (for Table View)
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) 
{
    if indexPath.row == (yourdataArray.count - 1) 
    {
        print("came to last row")
    }
}

//Show last cell (for Collection View)
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) 
{
    if indexPath.row == (yourdataArray.count - 1)
    {
        // Last cell is visible
    }
}

Answer 6

对于Xcode 8和swift 3

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        let lastSectionIndex = tableView.numberOfSections - 1
        let lastRowIndex = tableView.numberOfRows(inSection: lastSectionIndex) - 1
        if indexPath.section ==  lastSectionIndex && indexPath.row == lastRowIndex {
            print("this is the last cell")
        }
    }

Answer 7

我找到了这个解决方案：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
      let contentOffsetMaxY: Float = Float(scrollView.contentOffset.y + scrollView.bounds.size.height)
      let contentHeight: Float = Float(scrollView.contentSize.height)
      let lastCellIsVisible = contentOffsetMaxY > contentHeight + somePaddingIfWanted
      if lastCellIsVisible {
           doSomething()
      }
}

Answer 8

我在使用willDisplayCell方法时遇到了一些问题。这对我有用：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let y = scrollView.contentOffset.y/(scrollView.contentSize.height - scrollView.frame.size.height)
    let relativeHeight = 1 - (table.rowHeight / (scrollView.contentSize.height - scrollView.frame.size.height))
    if y >= relativeHeight{
        print("last cell is visible")
    }
}

只需在委托方法中传递它，并将'table'更改为tableView。

UITableView检测最后一个单元格

8 个答案: