更改单元格高度后，UITableView在滚动时跳动 [英] UITableView jumpy on scroll after changing cell height

问题描述

所以我有一个tableView，我想在点击时更改单元格的高度。好吧，实际上，我正用一个更大的细胞替换它。
点击，我打电话：

So I have a tableView where I want to change the height of a cell when tapped. Well, actually, I am replacing it with a bigger cell. On tap, I call:

tableView.beginUpdates()
tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
tableView.endUpdate()

然后我修改我的 cellForRowAtIndexPath 返回正确的新单元格和高度。通过在单元格的实现中覆盖 sizeThatFits 自动计算单元格的高度：

And then I modify my cellForRowAtIndexPath to return the right new cell and height. The cell's height is being automatically calculated by overriding sizeThatFits in the cell's implementation:

override func sizeThatFits(size: CGSize) -> CGSize {
    return CGSizeMake(size.width, myHeight)
}

奇怪在我这样做之后，向下滚动很好，但是当我向上滚动时，桌子每秒跳跃5个左右的像素，直到我到达顶部。在我到达桌面顶部后，问题就消失了，任何一个方向都没有跳跃。知道为什么会这样吗？我想它与新的单元格高度取代其他单元格有关，但我不明白为什么tableView没有处理这个问题。任何帮助表示赞赏！

Oddly enough, after I do this, scrolling downwards is fine, but when I scroll upwards, the table jumps 5 or so pixels every second until I reach the top. After I reach the top of the table, the problem is gone and there is no jumping going in either direction. Any idea why this is happening? I imagine it has something to do with the new cell height displacing the other cells, but I can't see why the tableView is not taking care of this. Any help is appreciated!

谢谢！

编辑：从cellForRowAtIndexPath添加代码：

Added code from cellForRowAtIndexPath:

 if self.openedCellIndex != nil && self.openedCellIndex == indexPath {
     cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as ListCell
     (cell as ListCell).updateWithDetailView(dayViewController!.view)
 } else {
     cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as ListCell
     (cell as ListCell).updateWithData(eventDay: store.events![indexPath.row], reminderDay: store.reminders![indexPath.row])
 }
 return cell

推荐答案

不幸的是，似乎没有一个简单的答案。我在多个iOS应用程序上一直在努力。

Unfortunately, there does not seem to be a simple answer to this. I have struggled with it on multiple iOS apps.

我找到的唯一解决方案是再次出现时以编程方式滚动到UITableView的顶部。

The only solution I have found is to programmatically scroll to the top of your UITableView once it appears again.

[self.tableView setContentOffset:CGPointMake(0, 0 - self.tableView.contentInset.top) animated:YES];

OR

self.tableView.contentOffset = CGPointMake(0, 0 - self.tableView.contentInset.top);

希望这是一个可接受的解决方案，同时仍能使用动态单元格高度=）

Hope this an acceptable work around while still being able to use dynamic cell heights =)

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