blocks|key|4585318|text|苹果将iOS8中的默认行高更改为UITableViewAutomaticDimension，并将其声明为-1。这意味着表视图已设置为自动计算单元格高度。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4585319|您需要实现autoLayout+(推荐)或实现新的委托方法：heightForRowAtIndexPath。这里有一个关于自动布局的好问题：Using+Auto+Layout+in+UITableView+for+dynamic+cell+layouts+&+variable+row+heights|4585320|不过，看起来你已经有效地硬编码了44+(旧的默认设置)，所以你可以直接这么做(不推荐)。|4585321|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/18746929/using-auto-layout-in-uitableview-for-dynamic-cell-layouts-variable-row-heights^0|G|T|1G|2|0|U|N|1Y|28|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|H|3|I|5|6|7|12|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

Apple changed the default row height in iOS8 to <code>UITableViewAutomaticDimension</code>, which is declared as <code>-1</code>. This means that your table view is set up for automatic cell height calculation.

You will either need to implement autoLayout (recommended) or implement the new delegate method: <code>heightForRowAtIndexPath</code>. Here's a great question about auto layout: <a href="https://stackoverflow.com/questions/18746929/using-auto-layout-in-uitableview-for-dynamic-cell-layouts-variable-row-heights">Using Auto Layout in UITableView for dynamic cell layouts &amp; variable row heights</a>

Seems like you were effectively hard coding 44 (the old default) anyway, though, so you could just do that (not recommended).

blocks|key|4585355|text|这让我挣扎了好几个小时。我最终将该值硬编码为44：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4585356|self.tableView.rowHeight+=+44;|code-block|syntax|javascript|4585357|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|$]]

This made me struggle for hours. I ended up hard coding the value to 44:

<pre><code>self.tableView.rowHeight = 44;
</code></pre>

blocks|key|4585414|text|实现heightForRowAtIndexPath会带来性能上的损失，当表中的所有行的高度都相同并且在运行时不会发生变化时(每次显示表时，每行调用一次)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4585415|在这种情况下，我继续在XIB中设置“行高”，并在需要rowHeight时使用以下对iOS+8友好的代码(它也适用于iOS+7及更低版本)。|4585416|NSInteger+aRowHeight+=+self.tableView.rowHeight;
if+(-1+==+aRowHeight)
{
++++aRowHeight+=+44;
}|code-block|syntax|javascript|4585417|这允许您在XIB中自由编辑行高，即使Apple在将来修复了此错误/功能，并且XIB+set+Row+Height+=+44停止返回为-1，它也将正常工作。|4585418|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

There is a performance penalty for implementing heightForRowAtIndexPath that I prefer not to incur when all rows in a table are the same height and never change at runtime (it is called once for every row, each time the table is displayed). 

In this situation, I continue to set "Row Height" in the XIB and use the following iOS 8 friendly code when I need rowHeight (it works on iOS 7 and below too).

<pre><code>NSInteger aRowHeight = self.tableView.rowHeight;
if (-1 == aRowHeight)
{
 aRowHeight = 44;
}
</code></pre>

This allows you to keep freely editing Row Height in the XIB and will work even if Apple fixes this bug/feature in the future and a XIB set Row Height = 44 stops coming back as -1.

blocks|key|4585449|text|另一个注意事项是，如果基于现有视图尺寸计算高度，则可能会在viewDidLayoutSubviews之前调用heightForRowAtIndexPath方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4585450|在这种情况下，覆盖viewDidLayoutSubviews，并重新计算所有可见单元格的frame.size.height值。|4585451|entityMap^0|T|L|1I|N|0|9|L|18|H|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

One more consideration is that if you are calculating the height based on existing view dimensions, the <code>heightForRowAtIndexPath</code> method may be called before <code>viewDidLayoutSubviews</code>.

In this case, override <code>viewDidLayoutSubviews</code>, and recalculate the <code>frame.size.height</code> value for all the visible cells.

blocks|key|4585483|text|我对这个问题的解决方案是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4585484|@interface+MCDummyTableView+()+<UITableViewDataSource,+UITableViewDelegate>
@end

@implementation+MCDummyTableView

++++-+(instancetype)+initWithFrame:(CGRect)frame+style:(UITableViewStyle)style+{
++++++++frame+=+(CGRect){+0,+0,+100,+100+};

++++++++self+=+[super+initWithFrame:frame+style:style];
++++++++if(!self)+return+self;

++++++++self.dataSource+=+self;
++++++++self.delegate+=+self;

++++++++[self+registerClass:[UITableViewCell+class]+forCellReuseIdentifier:@"CELL"];

++++++++return+self;
++++}

++++-+(NSInteger)+numberOfSections+{
++++++++return+1;
++++}

++++-+(NSInteger)+tableView:(UITableView+*)tableView+numberOfRowsInSection:(NSInteger)section+{
++++++++return+1;
++++}

++++-+(UITableViewCell*)+cellForRowAtIndexPath:(NSIndexPath*)indexPath+{
++++++++/*
++++++++++++UITableView+doesn't+want+to+generate+cells+until+it's+in+the+view+hiearchy,+this+fixes+that.
++++++++++++However,+if+this+breaks+(or+you+don't+like+it)+you+can+always+add+your+UITableView+to+a+UIWindow,+then+destroy+it
++++++++++++(that+is+likely+the+safer+solution).
++++++++*/

++++++++return+[self.dataSource+tableView:self+cellForRowAtIndexPath:indexPath];
++++}

++++-+(UITableViewCell*)+tableView:(UITableView*)tableView+cellForRowAtIndexPath:(NSIndexPath*)indexPath+{
++++++++return+[self+dequeueReusableCellWithIdentifier:@"CELL"];
++++}

++++-+(CGFloat)+defaultRowHeight+{
++++++++return+[self+cellForRowAtIndexPath:[NSIndexPath+indexPathForRow:0+inSection:0]].frame.size.height;
++++}

@end|code-block|syntax|javascript|4585485|我真的不喜欢硬编码的东西。我使用这个类在应用程序的早期缓存默认的单元格高度。|4585486|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

My solution to this problem:

<pre><code>@interface MCDummyTableView () &lt;UITableViewDataSource, UITableViewDelegate&gt;
@end

@implementation MCDummyTableView

 - (instancetype) initWithFrame:(CGRect)frame style:(UITableViewStyle)style {
 frame = (CGRect){ 0, 0, 100, 100 };

 self = [super initWithFrame:frame style:style];
 if(!self) return self;

 self.dataSource = self;
 self.delegate = self;

 [self registerClass:[UITableViewCell class] forCellReuseIdentifier:@"CELL"];

 return self;
 }

 - (NSInteger) numberOfSections {
 return 1;
 }

 - (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
 return 1;
 }

 - (UITableViewCell*) cellForRowAtIndexPath:(NSIndexPath*)indexPath {
 /*
 UITableView doesn't want to generate cells until it's in the view hiearchy, this fixes that.
 However, if this breaks (or you don't like it) you can always add your UITableView to a UIWindow, then destroy it
 (that is likely the safer solution).
 */

 return [self.dataSource tableView:self cellForRowAtIndexPath:indexPath];
 }

 - (UITableViewCell*) tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
 return [self dequeueReusableCellWithIdentifier:@"CELL"];
 }

 - (CGFloat) defaultRowHeight {
 return [self cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]].frame.size.height;
 }

@end
</code></pre>

I really don't like hardcoding things. I use this class to cache the default cell height early on in the app.

blocks|key|4585525|text|如果您意外地将IB中的行高从44更改为其他值(如40)，则自动计算单元格大小将失败。你欠我3小时，苹果。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4585526|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

If you accidentally change the row height in IB from 44 to something else (like 40), automatic cell size calculation fails. You owe me 3 hours, Apple.

The code I used to create a rectangle (at least until iOS7) was

<pre><code>CGRect rect = [cTableView frame];
rect.origin.y += [cTableView rowHeight];
searchOverlayView = [[BecomeFirstResponderControl alloc] initWithFrame:rect];
</code></pre>

On iOS7, <code>cTableView</code> (an instance of a <code>UITableView</code>) returned <code>44</code>. Testing in iOS8 with an iPhone 5s returns <code>-1</code>. 

Why is this happening? What is the correct code that needs to be used in order for my app to be backwards compatible with iOS7?

Wrong value from UITableView:rowHeight at iOS8

我用来创建矩形(至少在iOS7之前)的代码是CGRect rect = [cTableView frame];rect.origin.y += [cTableView rowHeight];searchOverlayView = [[BecomeFirstResponderControl alloc] initWith...

问UITableView中的值错误: iOS8处的行高
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