blocks|key|4282196|text|如您所愿！这里有一些使用Autolayout的指南，应该会有很大帮助。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4282197|首先，理想的方法是在Interface+Builder中进行设置，这样就不需要进一步的编程了。因此，如果--例如--你的视图的边界发生了变化，那么你的视图会根据需要自动调整。|4282198|如果这样做不起作用，那么您可能必须以编程方式更新约束。现在，正如我所提到的，金科玉律就是更新约束。抵制住更新底层UIView框架的诱惑！|offset|length|style|CODE|4282199|因此，您将执行以下操作：|4282200|_myWidthConstraint.constant+=+300.f;|code-block|syntax|javascript|4282201|下一件要注意的事情是，您应该在特定的位置执行此操作，即在UIView子类方法updateConstraints中执行此操作|4282202|-+(void)updateConstraints
{
++++[super+updateConstraints];
++++_myWidthConstraint.constant+=+300.f;
}|4282203|你是如何触发的？通过调用：|4282204|++++[self+setNeedsUpdateConstraints];|4282205|希望这能有所帮助！有关更多信息，请查看Ole+Begemann的优秀文章10+Things+You+Need+To+Know+About+Cocoa+Autolayout。|4282206|别忘了WWDC的视频。这些是必不可少的！|4282207|另外，现在有一本书叫iOS+Auto+Layout+Demystified+。虽然我已经买了，但我还没有机会去读它。不过它看起来确实很不错。|4282208|entityMap|0|LINK|mutability|MUTABLE|url|http://oleb.net/blog/2013/03/things-you-need-to-know-about-cocoa-autolayout/|1|https://rads.stackoverflow.com/amzn/click/com/B00C68XS0S^0|0|0|1K|6|0|0|0|S|6|12|H|0|0|0|0|10|1D|0|0|0|A|S|1|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1G|8|@$F|1H|G|1I|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1J|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1K|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1L|8|@$F|1M|G|1N|H|I]|$F|1O|G|1P|H|I]]|9|@]|A|$]]|$1|S|3|T|5|N|7|1Q|8|@]|9|@]|A|$O|P]]|$1|U|3|V|5|6|7|1R|8|@]|9|@]|A|$]]|$1|W|3|X|5|N|7|1S|8|@]|9|@]|A|$O|P]]|$1|Y|3|Z|5|6|7|1T|8|@]|9|@$F|1U|G|1V|1|1W]]|A|$]]|$1|10|3|11|5|6|7|1X|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|1Y|8|@]|9|@$F|1Z|G|20|1|21]]|A|$]]|$1|14|3|-4|5|6|7|22|8|@]|9|@]|A|$]]]|15|$16|$5|17|18|19|A|$1A|1B]]|1C|$5|17|18|19|A|$1A|1D]]]]

As requested! Here's some guidelines for using Autolayout that should help a lot. 

The first thing is that the ideal approach is for you to set things up in Interface Builder so that no further programming is required. So, if - for example - the bounds of your view change, then your view will adjust itself automatically as required.

If that doesn't do the business, then you may have to update the constraints programmatically. Now, the golden rules as I mentioned is that you update the constraints. Resist the temptation to update the underlying <code>UIView</code> frame! 

So, you'll do something like:

<pre><code>_myWidthConstraint.constant = 300.f;
</code></pre>

The next thing to note is that you should do this in a specific place, and that is in your <code>UIView</code> subclass method <code>updateConstraints</code>:

<pre><code>- (void)updateConstraints
{
 [super updateConstraints];
 _myWidthConstraint.constant = 300.f;
}
</code></pre>

How do you trigger that? By invoking:

<pre><code> [self setNeedsUpdateConstraints];
</code></pre>

Hope this helps! For further info check Ole Begemann's excellent article <a href="http://oleb.net/blog/2013/03/things-you-need-to-know-about-cocoa-autolayout/" rel="noreferrer">10 Things You Need To Know About Cocoa Autolayout</a>.

Don't forget the WWDC videos. These are essential! 

Also, now there's a book <a href="https://rads.stackoverflow.com/amzn/click/com/B00C68XS0S" rel="noreferrer" rel="nofollow noreferrer">iOS Auto Layout Demystified </a>. Although I've bought it, I haven't had a chance to read it yet. It does look pretty good though.

blocks|key|2021871|text|我也面临着同样的问题。imageview中的图像对于imageview来说太大，并且contentMode被设置为AspectFill。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2021872|我通过取消勾选的自动调整子视图来解决这个问题。|BOLD|2021873|📷|atomic|2021874|​|2021875|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/18b81d2270287ea42ac51b282b1e662d.png|imageAlt^0|16|B|1L|A|0|3|4|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|14|8|@]|D|@$9|15|A|16|1|17]]|E|$]]|$1|L|3|M|5|6|7|18|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|O|$P|$5|Q|R|S|E|$T|U|V|-4]]]]

I was also facing the same issue. the image inside the imageview was too big for the imageview and the <code>contentMode</code> was set to <code>AspectFill</code>.

I solved this by unchecking 'Autoresize Subviews".
<img src="https://i.stack.imgur.com/KeUQp.png" alt="enter image description here">

Sorry for the bother but I'm trying to lazy load several imageViews and then resize it proportionately to the content in a UITableView. I'm also trying (Unwisely perhaps?) to use Autolayout basically for the first time. And I'm not understanding why the constraints aren't working in this case. Here's the code that I'm using to resize the UIImageView after I've loaded the proper image into it.

<pre><code>// Scale the image view and return it.
- (UIImageView *) scaleImageViewForScreenWidth:(UIImageView *)imageView {
 UIImage *imgFromView = [imageView image];
 CGRect newFrame = CGRectMake(0, 0, imgFromView.size.width, imgFromView.size.height);

 float imgFactor = newFrame.size.height / newFrame.size.width;
 newFrame.size.width = [[UIScreen mainScreen] bounds].size.width;
 newFrame.size.height = newFrame.size.width * imgFactor;
 [imageView setFrame:newFrame];
 return imageView;
}
</code></pre>

As far as constraints are concerned. I'm trying to attach a Label and UIImageView with a shadow to the bottom of the main imageview. Here are the constraints that I'm applying to a bottom shadow in the imageview. The bottom shadow constraints are:

<pre><code>Height Equals: 83
Align Bottom to: Background Image View
LeadingSpace to: Table View Cell
</code></pre>

I'm not getting what I want though. Any ideas? I feel like I'm fighting autolayout.

Autolayout UIImageView with programatic re-size not following constraints

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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很抱歉给您带来麻烦，但我正在尝试延迟加载几个imageViews，然后根据UITableView中的内容按比例调整它的大小。我也在尝试(也许是不明智的？)基本上第一次使用Autolayout。我不明白为什么约束在这种情况下不起作用。下面是我在加载适当的图像后用来调整UIImageView大小的代码。// Scale t...

问具有可编程调整大小的自动布局UIImageView不遵循约束
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问具有可编程调整大小的自动布局UIImageView不遵循约束EN