But more importantly, the label is positioned by passing its layout constraint to the parent.

但更为重要的是，该标签是通过将其布局约束传递给父元素来定位的。

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Left-aligned labels have a tidier, clear layout and they enable users to quickly scan each label increasing the readability of the labels.

标签左对齐的表单通常有更整齐、更清晰的布局，它们能使用户快速的扫视每个标签，这增加了标签的可读性。

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For example, if the earlier label displayed HTML-formatted text and the new text is plain and simple, the layout must change accordingly.

例如，如果旧的标签显示html格式的文本，而新的文本是简单的纯文本格式，那么就要相应地更改布局。

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Now, auto layout interprets UILayoutAttributeBottom as the bottom of the text box (presuming the label is not bigger than its intrinsic content size) and UILayoutAttributeBaseline as the baseline of the text.

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