UITableViewCellContentView 高度怎么可能与 heightForRowAtIndexPath 不同: [英] How is it possible that UITableViewCellContentView height is different from heightForRowAtIndexPath:

问题描述

我的 UITableView 遇到了一个非常奇怪的问题.我有一些不同的单元格要显示在类似新闻源的表格视图中.

I'm facing a really weird problem on my UITableView. I have some different cells that I want to display on a newsfeed-like table view.

重复使用后的单元格出现问题.该单元格包含两个图像、两个标签和一个带有分享/喜欢/评论按钮的视图.我会试着画它，但我不确定它会不会漂亮:

And I have a problem with a cell after reuse. The cell contains two images, two labels and a view with the share/like/comment buttons. I'm gonna try to draw it, but I'm not sure it's gonna be pretty :

-------------------------------------------------
|       |   __    ____________________________  |
|       |  |_2|  |                            | |
|       |        |              3             | |
|       |        |                            | |
|   1   |        |____________________________| |
|       |                                       |
|       |_______________________________________|
|       |                                       |
|       |                  4                    |
|_______|_______________________________________|
|                                               |
|                       5                       |
|_______________________________________________|

1 : objectImage
2 : subjectImage
3 : titleLabel
4 : commentLabel
5 : actionsView

我的限制是:

"H:|-0-[objectImage(60)]-7-[subjectImage(30)]-7-[titleLabel]-7-|"
"H:|-0-[objectImage(60)]-0-[commentLabel]-0-|"
"H:|-0-[actionsView]-0-|"
"V:|-0-[objectImage(>=35)]-0-[actionsView(44)]-0-|"
"V:|-7-[subjectImage(30)]"
"V:|-7-[titleLabel(>=46)]-7-[commentLabel(>=35)]-0-[actionsView(44)]-0-|"

并且每次绘制单元格时，我都会更改此约束:

And every time the cell is drawn, I change this constraint:

"V:[commentLabel(%0.2f)]"

单元格第一次完美显示.

The cells display perfectly the first time.

但是，我遇到的问题是，在某个时间点，经过一些重用(我无法每次都重现它)，应用程序由于约束问题而崩溃.这是一个例外:

But, the problem I have is that at a point, after some reuse (I can't reproduce it every time) the app crashes because of a constraint problem. Here is the exception:

"<NSLayoutConstraint:0x205a75b0 V:[UILabel:0x1ef31430(105)]>",
"<NSLayoutConstraint:0x1ef34440 V:[UILabel:0x1ef31430]-(0)-[UIView:0x1ef2fe50]>",
"<NSLayoutConstraint:0x1ef34380 V:[UILabel:0x1ef31250]-(7)-[UILabel:0x1ef31430]>",
"<NSLayoutConstraint:0x1ef33900 V:|-(7)-[UILabel:0x1ef31250]   (Names: '|':UITableViewCellContentView:0x1ef2bf50 )>",
"<NSLayoutConstraint:0x1ef34340 V:[UILabel:0x1ef31250(>=46)]>",
"<NSLayoutConstraint:0x1ef33210 V:[UIView:0x1ef2fe50]-(0)-|   (Names: '|':UITableViewCellContentView:0x1ef2bf50 )>",
"<NSLayoutConstraint:0x1ef331d0 V:[UIView:0x1ef2fe50(44)]>",
"<NSAutoresizingMaskLayoutConstraint:0x1ef36f90 h=--& v=--& V:[UITableViewCellContentView:0x1ef2bf50(147)]>"


Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1ef34380 V:[UILabel:0x1ef31250]-(7)-[UILabel:0x1ef31430]>

问题是约束 [UITableViewCellContentView:0x1ef2bf50(147)] 不正确.

The problem is that the constraint [UITableViewCellContentView:0x1ef2bf50(147)] is not right.

奇怪的是，heightForRowAtIndexPath: 返回的正确值是 217.

What is weird is that the heightForRowAtIndexPath: returns the correct value which is 217.

而我不明白的是 UITableViewCell 的高度是正确的！

And what I don't understand is that the height of the UITableViewCell is correct!

(lldb) po 0x1ef2bf50
$0 = 519225168 <UITableViewCellContentView: 0x1ef2bf50; frame = (0 0; 320 147); gestureRecognizers = <NSArray: 0x1ef30a20>; layer = <CALayer: 0x1ef2a3d0>>
(lldb) po [0x1ef2bf50 superview]
$1 = 0x1ef30e40 <NewsSubjectCommentCell: 0x1ef30e40; baseClass = UITableViewCell; frame = (0 1055; 320 217); hidden = YES; autoresize = W; layer = <CALayer: 0x1ef25e10>>

所以我不明白 UITableViewCellContentView 的高度约束怎么可能是147，是另一个同类型单元格的高度，但是应该改成209吧?

So I don't understand how is it possible that the height constraint of UITableViewCellContentView is 147. It is the height of another cell of the same type, but it should be changed to 209, right?

所以，如果您对这是如何发生的有任何见解(也许我做错了什么)，我会很高兴.

So, if you have any insight on how this can happen (maybe I did something wrong), I'd be glad.

谢谢，

推荐答案

我在这里找到了答案:iOS7 UITableViewCell 中的自动布局约束问题

我们只需要将 contentView 的 AutoresizingMask 设置为 UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth 并...问题解决了！

We just have to set the AutoresizingMask of the contentView to UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth and ... problem solved!

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