的UILabel sizeToFit和约束 [英] UILabel sizeToFit and constraints

问题描述

有没有简单的方法，可以帮助我改变相关视图位置动态使用他们的内容大小？

Is there any simple way which can help me to change position of dependent views dynamically using their content size?

我要显示在列几个视图，所有有不同的内容。而且我要他们放置了一个又一个（我已经创建使用约束它看起来像这样的布局）

I want to show several views in column which all have varying content. And I want them to be placed one after another (I've created layout using constraints which looks like this)

但每当我改变标签和通话内容 sizeToFit ，系统似乎忽略布局。

But whenever I change content of labels and call sizeToFit, system seems to ignore layout.

目前，我感兴趣的只是height属性，我知道矩形约束还可以用在过去，我写了很多UIView的类别来动态改变大小（我想每个人都一样）。但是，也许有一个简单的方法，我不知道吗？

At the moment I'm interested only in height property, I know that constraining rect can be used too and in the past I wrote many categories on UIView to change sizes dynamically (I guess everyone did). But maybe there is a simple way which I don't know?

推荐答案

-sizeToFit 如果您正在使用自动布局不应该被调用。这就是老系统的一部分。

-sizeToFit should not be called if you are using auto-layout. That's part of the 'old' system.

它看起来像IB已经明确插入到高度的限制（垂直条旁边的标签标明这一点）。请尝试选择标签，打Cmd的+ =清除这些。

It looks like IB has inserted explicit heights into your constraints (the vertical bars next to the labels indicate this). Try selecting the labels and hitting Cmd+= to clear these.

有关多行标签，你也需要做你的视图控制器下面，使一切正常工作时旋转/缩放视图：

For multiline labels you will also need to do the following in your view controller to make everything work correctly when rotating/resizing the view:

- (void)updateLabelPreferredMaxLayoutWidthToCurrentWidth:(UILabel *)label
{
    label.preferredMaxLayoutWidth =
        [label alignmentRectForFrame:label.frame].size.width;
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    [self updateLabelPreferredMaxLayoutWidthToCurrentWidth:self.label1];
    [self updateLabelPreferredMaxLayoutWidthToCurrentWidth:self.label2];
    [self updateLabelPreferredMaxLayoutWidthToCurrentWidth:self.label3];

    [self.view layoutSubviews];
}

多标签揭露自动布局的弱点之一。我们必须更新 preferredMaxLayoutWidth 来强制标签回流，并调整其高度，否则，如果视图大小/旋转，自动布局并没有意识到标签需求将回流和调整大小。

Multiline labels expose one of the weaknesses of auto-layout. We have to update preferredMaxLayoutWidth to force the label to reflow and adjust its height, otherwise if the view is resized/rotated, auto-layout does not realize the label needs to be reflowed and resized.

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