Header in Swift 的 TableView 的自定义分页大小（一次滚动一个单元格）

Question

我有一个包含多个部分的 UITableView，每个部分都有一个 header。 table 的大小使得一个 header 和一个单元格占据了 table 的整个框架。我想允许用户一次只滚动 table 一个单元格。当我设置 paging = enabled 时，滚动不会按预期工作，因为 table 一次滚动整个 table 帧，而不是一次滚动一个单元格。这会导致不希望的偏移量随着您滚动 table 而不断变大。

到目前为止，我的研究表明我需要覆盖 scrollViewWillBeginDragging。参见示例 UITableView with custom paging-like behaviour。但是我读到的关于这个话题的每个 post 肯定都在 Swift 之前，因为它都在 Objective C.

中

请建议 Swift 代码以完成带有 header 节的 table 视图的单个单元格分页。尽管可能需要禁用分页本身，但解决方案应尽可能接近真正的分页。

下面是我 table 尺码的代码。 table 的帧大小是 475。

func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    if (condition == true) {
        return CGFloat(425)
    }
    else {
        return CGFloat(375)
    }
}

func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {

    if (condition == true) {
        return CGFloat(47)
    }
    else {
        return CGFloat(90)
    }
}

更新： 这里的最佳答案 (Force UITableView to Scroll to Tops of Cells) 似乎也很相关。但是，同样，这一切都在 Objective C 中。如果这些链接中的任何一个答案被证明是正确的，将该答案简单翻译成 Swift 就足够了。

更新 2 我几乎明白了。但是边缘情况不起作用（即，在 table 的最顶部和最底部）。也就是说，我得到一个 paging-like 滚动动作，除非我尝试向下滚动到 table 中的最后一个单元格。没有捕捉到最后一个单元格。它只是正常滚动。我怀疑它与最后一个单元格的 frame.origin.y 有关。

请帮我找出这些边缘情况。代码如下：

viewDidLoad() {
      self.tableView.decelerationRate = UIScrollViewDecelerationRateFast
}

var lastContentOffset:CGPoint!
var initialIndexPath:NSIndexPath?
func scrollViewWillBeginDragging(scrollView: UIScrollView) {
    lastContentOffset = CGPointMake(scrollView.contentOffset.x, scrollView.contentOffset.y)
    var visibleCellIndexes = tableView.indexPathsForVisibleRows() as! [NSIndexPath]
    initialIndexPath = visibleCellIndexes[0]
}



var scrolledToPath:NSIndexPath?
func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    if (scrollView == self.tableView) {


        var lastIndexPath:NSIndexPath!
        var nextIndexPath:NSIndexPath!
        if let p = scrolledToPath {
            lastIndexPath = scrolledToPath
        }
        else if let u = initialIndexPath {
            lastIndexPath = initialIndexPath
        }
        if (lastContentOffset.y <= scrollView.contentOffset.y) {
            // scrolling down
            if (lastIndexPath.row == numRows(lastIndexPath.section)-1) {
                // last row in section
                if (lastIndexPath.section == numSections(self.tableView)-1) {
                    // last  section
                    nextIndexPath = lastIndexPath
                }
                else {
                    nextIndexPath = NSIndexPath(forRow: 0, inSection: lastIndexPath.section+1)
                }
            }
            else {
                nextIndexPath = NSIndexPath(forRow: lastIndexPath.row+1, inSection: lastIndexPath.section)
            }
        }
        else if (lastContentOffset.y > scrollView.contentOffset.y) {
            // scrolling up
            if (lastIndexPath.row == 0) {
                // first row in section
                if (lastIndexPath.section == 0) {
                    // first section
                    nextIndexPath = lastIndexPath
                }
                else {
                    nextIndexPath = NSIndexPath(forRow: numRows(lastIndexPath.section-1)-1, inSection: lastIndexPath.section-1)
                }
            }
            else {
                nextIndexPath = NSIndexPath(forRow: lastIndexPath.row-1, inSection: lastIndexPath.section)
            }

        }

        scrolledToPath = nextIndexPath

        var headerHeight = CGFloat(47)
        if (condition == true) {
            headerHeight = CGFloat(90)
        }

        var rectOfNextIndexPath:CGRect = self.tableView.rectForRowAtIndexPath(nextIndexPath)
        targetContentOffset.memory.y = rectOfNextIndexPath.origin.y - headerHeight

    }
}

Answer 1

已修复。在我的 tableview 中调整大小弄乱了最终案例。在我确定单元格大小正确后，效果很好。下面是swift.

中tableview的page-like scrolling的解决方案

viewDidLoad() {
      self.tableView.decelerationRate = UIScrollViewDecelerationRateFast
}

var lastContentOffset:CGPoint!
var initialIndexPath:NSIndexPath?
func scrollViewWillBeginDragging(scrollView: UIScrollView) {
    lastContentOffset = CGPointMake(scrollView.contentOffset.x,     scrollView.contentOffset.y)
    var visibleCellIndexes = tableView.indexPathsForVisibleRows() as! [NSIndexPath]
    initialIndexPath = visibleCellIndexes[0]
}



var scrolledToPath:NSIndexPath?
func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {

    var lastIndexPath:NSIndexPath!
    var nextIndexPath:NSIndexPath!
    if let p = scrolledToPath {
        lastIndexPath = scrolledToPath
    }
    else if let u = initialIndexPath {
        lastIndexPath = initialIndexPath
    }
    if (lastContentOffset.y <= scrollView.contentOffset.y) {
        // scrolling down
        if (lastIndexPath.row == numRows(lastIndexPath.section)-1) {
            // last row in section
            if (lastIndexPath.section == numSections(self.tableView)-1) {
                // last  section
                nextIndexPath = lastIndexPath
            }
            else {
                nextIndexPath = NSIndexPath(forRow: 0, inSection: lastIndexPath.section+1)
            }
        }
        else {
            nextIndexPath = NSIndexPath(forRow: lastIndexPath.row+1, inSection: lastIndexPath.section)
        }
    }
    else if (lastContentOffset.y > scrollView.contentOffset.y) {
        // scrolling up
        if (lastIndexPath.row == 0) {
            // first row in section
            if (lastIndexPath.section == 0) {
                // first section
                nextIndexPath = lastIndexPath
            }
            else {
                nextIndexPath = NSIndexPath(forRow: numRows(lastIndexPath.section-1)-1, inSection: lastIndexPath.section-1)
            }
        }
        else {
            nextIndexPath = NSIndexPath(forRow: lastIndexPath.row-1, inSection: lastIndexPath.section)
        }

    }

    scrolledToPath = nextIndexPath

    var headerHeight = CGFloat(47)
    if (condition == true) {
        headerHeight = CGFloat(90)
    }

    var rectOfNextIndexPath:CGRect = self.tableView.rectForRowAtIndexPath(nextIndexPath)
    targetContentOffset.memory.y = rectOfNextIndexPath.origin.y - headerHeight


}

Header in Swift 的 TableView 的自定义分页大小（一次滚动一个单元格）

Custom Paging Size for TableView with Header in Swift (Scroll One Cell At a Time)

tableview

custom-paging

swift