blocks|key|250304|text|不能更改现有UITableViewCell的高度。您要告诉UITableView单元格无效，然后重新加载它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|250305|在重新加载单元格(cellForRowAtIndexPath)时，您可以传递新的更新的单元格。使用tableView.reloadRowsAtIndexPaths([indexPath],+withRowAnimation:+.Fade)触发单个单元格刷新。|250306|reloadRowsAtIndexPaths并没有reloadData()那么激烈。这是一个准时的索引刷新，不需要被tableView.beginUpdates和tableView.endUpdates包围，您可以提供自己选择的动画方法，比如.Fade。|250307|参见reloadRowsAtIndexPaths(_:withRowAnimation:)中的文档。|250308|还可以访问这个堆栈溢出回答，它详细描述了更改单元格高度的情况。|250309|​|250310|📷|atomic|250311|250312|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableView_Class/#//apple_ref/occ/instm/UITableView/reloadRowsAtIndexPaths:withRowAnimation:|1|https://stackoverflow.com/a/34997679/218152|2|IMAGE|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/a58c4ec8866f60dc9276585a0638726d.gif|imageAlt^0|6|F|T|B|0|9|L|1D|1Y|0|0|M|P|C|1M|M|29|K|3D|5|0|2|17|1B|2|0|0|5|8|1|0|0|0|1|2|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1J|8|@$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]|$9|1Q|A|1R|B|C]|$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|1U|8|@$9|1V|A|1W|B|C]]|D|@$9|1X|A|1Y|1|1Z]]|E|$]]|$1|L|3|M|5|6|7|20|8|@]|D|@$9|21|A|22|1|23]]|E|$]]|$1|N|3|O|5|6|7|24|8|@]|D|@]|E|$]]|$1|P|3|Q|5|R|7|25|8|@]|D|@$9|26|A|27|1|28]]|E|$]]|$1|S|3|O|5|6|7|29|8|@]|D|@]|E|$]]|$1|T|3|-4|5|6|7|2A|8|@]|D|@]|E|$]]]|U|$V|$5|W|X|Y|E|$Z|10]]|11|$5|W|X|Y|E|$Z|12]]|13|$5|14|X|15|E|$16|17|18|-4]]]]

You cannot change the height of an existing <code>UITableViewCell</code>. You want to tell the <code>UITableView</code> that cell is invalid, and reload it.

At the time the cell is reloaded (<code>cellForRowAtIndexPath</code>) you can then pass the new, updated cell. And you trigger a single cell refresh with <code>tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)</code>

<code>reloadRowsAtIndexPaths</code> is not as drastic are <code>reloadData()</code>. It is a punctual index refresh, does not need to be surrounded by <code>tableView.beginUpdates</code> and <code>tableView.endUpdates</code>, and you get to supply an animation method of your choice, such as <code>.Fade</code>.

See <code>reloadRowsAtIndexPaths(_:withRowAnimation:)</code> in the <a href="https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableView_Class/#//apple_ref/occ/instm/UITableView/reloadRowsAtIndexPaths:withRowAnimation:" rel="nofollow noreferrer">documentation</a>.

<hr>

Also visit <a href="https://stackoverflow.com/a/34997679/218152">this Stack Overflow answer</a> which describes changing a cell height in details.

<a href="https://i.stack.imgur.com/GHHUm.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GHHUm.gif" alt="Animated demo"></a>

blocks|key|153648|text|节流溶液|type|unstyled|depth|inlineStyleRanges|entityRanges|data|153649|reloadRowsAtIndexPaths的问题是，UITextField将resignFirstResponder，因为从本质上讲，单元是重新加载的:即销毁。|offset|length|style|CODE|153650|相反，beginUpdates()+&+endUpdates()确实维护现有的单元格，但是在包含scrollEnabled+UITextView的单元格上调用时会感到不安，如果每个textViewDidChange都被触发。|153651|限制更新频率|BOLD|153652|此解决方案基于流行的textViewDidChange方法，仅通过推迟更新来减少或停止闪烁。|153653|UITableViewCell**:**+子类|153654|class+TableViewTextViewCell+:+UITableViewCell,+UITextViewDelegate+{
++++var+refreshCell:(()+->+Void)?+=+nil
++++var+textViewDirtyCount+=+0

++++//+MARK:+-+UITextViewDelegate
++++func+textViewDidChange(_+textView:+UITextView)+{
++++++++textViewDirtyCount+%2B=+1
++++++++perform(#selector(TableViewTextViewCell.queuedTextVewDidChange),
++++++++++++++++with:+nil,
++++++++++++++++afterDelay:+0.3)+//+Wait+until+typing+stopped
++++}

++++func+textViewDidBeginEditing(_+textView:+UITextView)+{
++++++++textViewDirtyCount+=+0+//+initialize+queuedTextVewDidChange
++++}

++++func+textViewDidEndEditing(_+textView:+UITextView)+{
++++++++textViewDirtyCount+=+-1+//+prevent+any+further+queuedTextVewDidChange
++++}

++++func+queuedTextVewDidChange()+{
++++++++if+textViewDirtyCount+>+0+{
++++++++++++textViewDirtyCount+-=+1
++++++++++++if+0+==+textViewDirtyCount,+let+refreshCell+=+refreshCell+{
++++++++++++++++refreshCell()
++++++++++++}
++++++++}
++++}
}|code-block|syntax|javascript|153655|脱队列&更新闭包：|153656|override+func+tableView(_+tableView:+UITableView,+cellForRowAt+indexPath:+IndexPath)+->+UITableViewCell+{
++++let+cell+=+tableView.dequeueReusableCellWithIdentifier(
++++++++"cell",+forIndexPath:+indexPath)+as!+TableViewTextViewCell

++++cell.refreshCell+=+{
++++++++()+->+Void+in
++++++++tableView.beginUpdates()
++++++++tableView.endUpdates()
++++}
++++return+cell
}|153657|注意上次输入字符后的0.3秒延迟；如果上次更改后不足0.3秒，则不会进行任何更新。这大大减少了闪烁。|153658|​|153659|📷|atomic|153660|153661|↻重放动画|153662|GitHub上的►找到了这个解决方案，还有关于斯威夫特的其他详细信息。|153663|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/98d504731cc30a1e8dbb1036ec97abfa.gif|imageAlt|1|LINK|MUTABLE|url|2|https://github.com/SwiftArchitect/SO-35259289|3|http://swiftarchitect.com/recipes/#SO-35259289^0|0|0|M|R|B|13|K|0|3|E|K|C|1C|D|1Q|A|2I|H|0|0|6|0|A|H|0|0|H|L|2|0|F|0|0|0|9|0|0|0|0|0|1|0|0|0|0|5|1|0|0|6|2|N|4|3|0^^$0|@$1|2|3|4|5|6|7|1S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1T|8|@$D|1U|E|1V|F|G]|$D|1W|E|1X|F|G]|$D|1Y|E|1Z|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|20|8|@$D|21|E|22|F|G]|$D|23|E|24|F|G]|$D|25|E|26|F|G]|$D|27|E|28|F|G]|$D|29|E|2A|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|2B|8|@$D|2C|E|2D|F|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|2E|8|@$D|2F|E|2G|F|G]]|9|@]|A|$]]|$1|O|3|P|5|6|7|2H|8|@$D|2I|E|2J|F|L]|$D|2K|E|2L|F|L]|$D|2M|E|2N|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|S|7|2O|8|@]|9|@]|A|$T|U]]|$1|V|3|W|5|6|7|2P|8|@$D|2Q|E|2R|F|L]]|9|@]|A|$]]|$1|X|3|Y|5|S|7|2S|8|@]|9|@]|A|$T|U]]|$1|Z|3|10|5|6|7|2T|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|2U|8|@]|9|@]|A|$]]|$1|13|3|14|5|15|7|2V|8|@]|9|@$D|2W|E|2X|1|2Y]]|A|$]]|$1|16|3|12|5|6|7|2Z|8|@]|9|@]|A|$]]|$1|17|3|18|5|6|7|30|8|@]|9|@$D|31|E|32|1|33]]|A|$]]|$1|19|3|1A|5|6|7|34|8|@]|9|@$D|35|E|36|1|37]|$D|38|E|39|1|3A]]|A|$]]|$1|1B|3|-4|5|6|7|3B|8|@]|9|@]|A|$]]]|1C|$1D|$5|1E|1F|1G|A|$1H|1I|1J|-4]]|1K|$5|1L|1F|1M|A|$1N|1I]]|1O|$5|1L|1F|1M|A|$1N|1P]]|1Q|$5|1L|1F|1M|A|$1N|1R]]]]

<h1>Throttled Solution</h1>
The trouble with <code>reloadRowsAtIndexPaths</code> is that the <code>UITextField</code> will <code>resignFirstResponder</code> since the cell, in essence, is reloaded: i.e. destroyed.
Conversely, <code>beginUpdates()</code> &amp; <code>endUpdates()</code> do maintain the existing cells, yet jitters when invoked on a cell containing a <code>scrollEnabled</code> <code>UITextView</code> if triggered with every single <code>textViewDidChange</code>.
Limit the updates frequency
This solution is based on the popular <code>textViewDidChange</code> approach, only reduces or stops flickering entirely by postponing the update.
Subclass <code>UITableViewCell</code>:
<pre class="lang-swift prettyprint-override"><code>class TableViewTextViewCell : UITableViewCell, UITextViewDelegate {
 var refreshCell:(() -&gt; Void)? = nil
 var textViewDirtyCount = 0

 // MARK: - UITextViewDelegate
 func textViewDidChange(_ textView: UITextView) {
 textViewDirtyCount += 1
 perform(#selector(TableViewTextViewCell.queuedTextVewDidChange),
 with: nil,
 afterDelay: 0.3) // Wait until typing stopped
 }

 func textViewDidBeginEditing(_ textView: UITextView) {
 textViewDirtyCount = 0 // initialize queuedTextVewDidChange
 }

 func textViewDidEndEditing(_ textView: UITextView) {
 textViewDirtyCount = -1 // prevent any further queuedTextVewDidChange
 }

 func queuedTextVewDidChange() {
 if textViewDirtyCount &gt; 0 {
 textViewDirtyCount -= 1
 if 0 == textViewDirtyCount, let refreshCell = refreshCell {
 refreshCell()
 }
 }
 }
}
</code></pre>
Dequeue &amp; update closure:
<pre class="lang-swift prettyprint-override"><code>override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -&gt; UITableViewCell {
 let cell = tableView.dequeueReusableCellWithIdentifier(
 &quot;cell&quot;, forIndexPath: indexPath) as! TableViewTextViewCell

 cell.refreshCell = {
 () -&gt; Void in
 tableView.beginUpdates()
 tableView.endUpdates()
 }
 return cell
}
</code></pre>
<hr />
Notice the 0.3 seconds delay after the last character has been entered ; if less than 0.3 seconds has elapsed since the last change, no update takes place. This significantly reduces flickering.
<a href="https://i.stack.imgur.com/00uDU.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/00uDU.gif" alt="Frame Delay" /></a>
<a href="https://i.stack.imgur.com/00uDU.gif" rel="nofollow noreferrer">↻ replay animation</a>
<hr />
► Find this solution on <a href="https://github.com/SwiftArchitect/SO-35259289" rel="nofollow noreferrer">GitHub</a> and additional details on <a href="http://swiftarchitect.com/recipes/#SO-35259289" rel="nofollow noreferrer">Swift Recipes</a>.

blocks|key|250397|text|如果在调用beginUpdates之前禁用UIView动画，则该方法可以工作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|250398|//inside+of+cellForRowAtIndexPath
cell.performCellUpdates+=+{+[unowned+self]+in
++++UIView.setAnimationsEnabled(false)+++//the+secret+sauce,+prevents+the+jitter
++++self.tv.beginUpdates()
++++self.tv.endUpdates()
++++UIView.setAnimationsEnabled(true)++++//don't+forget+to+turn+animations+back+on
}
+++
...

//inside+of+cell+subclass
func+textViewDidChange(_+textView:+UITextView)+{
++++textView.sizeToFit()
++++performCellUpdates()
}|code-block|syntax|javascript|250399|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The beginUpdates method works if you disable UIView animations before calling it.
<pre><code>//inside of cellForRowAtIndexPath
cell.performCellUpdates = { [unowned self] in
 UIView.setAnimationsEnabled(false) //the secret sauce, prevents the jitter
 self.tv.beginUpdates()
 self.tv.endUpdates()
 UIView.setAnimationsEnabled(true) //don't forget to turn animations back on
}
 
...

//inside of cell subclass
func textViewDidChange(_ textView: UITextView) {
 textView.sizeToFit()
 performCellUpdates()
}
</code></pre>

I have a table view similar to the Compose screen in Mail, where one of the cells is used for text input. I'd like the cell to resize automatically by constraining the <code>contentView</code> of the cell to its <code>UITextView</code> subview using Auto Layout. The table view's <code>rowHeight</code> and <code>estimatedRowHeight</code> are set to <code>UITableViewAutomaticDimension</code>. Additionally, the text view's <code>scrollEnabled</code> property is set to <code>false</code> so that it reports its <code>intrinsicContentSize</code>.

However, the cell does not update its height as lines of text are entered by the user, even though the text view itself does update its intrinsic content size. As far as I know, the only way to request this manually is for the table view to call <code>beginUpdates()</code> and <code>endUpdates()</code>. The height of the cell is then correctly updated, but this also causes re-layout of the entire table view. Here's (someone else's) <a href="https://github.com/jurezove/self-sizing-uitextview-in-a-table" rel="nofollow noreferrer">sample code demonstrating the problem</a>.

How can I reflect changes in the cell's text view without laying out the entire table view?

Updating the Height of a Self-Sizing Table View Cell with a Text View

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个表视图，类似于Mail中的复合屏幕，其中一个单元格用于文本输入。我希望该单元格通过使用自动布局将单元格的contentView限制到其UITextView子视图来自动调整大小。表视图的rowHeight和estimatedRowHeight设置为UITableViewAutomaticDimension。此外，...

问用文本视图更新自调整表视图单元格的高度
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问用文本视图更新自调整表视图单元格的高度EN