ios自动布局:以编程方式设置宽度约束

ios auto-layout: Programmatically set width constraint(ios自动布局:以编程方式设置宽度约束)

问题描述

我正在开发一个 ios 应用程序.我正在以编程方式将自动布局添加到 2 个标签.

I am working on an ios application. I am adding the auto-layout programmatically to 2 labels.

我需要添加一个约束使它们的宽度相等.

I need to add a constraint to make them equal width.

我知道如何通过使用来固定标签的宽度:

I know how to fix the width of a label by using :

constraint = [NSLayoutConstraint
    constraintWithItem:myLabel
             attribute:NSLayoutAttributeWidth
            relatedBy:NSLayoutRelationEqual
              toItem: nil
           attribute:NSLayoutAttributeNotAnAttribute
          multiplier:1.0f
            constant:200.0f];

这会将标签大小固定为常数.但是我有 2 个标签，我希望它们具有相同的大小，而不必设置常量.

That would fix the label size to a constant. But I have 2 labels and I want them to have equal size without having to set a constant.

推荐答案

原来我只需要执行以下操作:

It turned out I just have to do the following:

constraint = [NSLayoutConstraint
    constraintWithItem:myLabel
        attribute:NSLayoutAttributeWidth
        relatedBy:NSLayoutRelationEqual
          toItem: otherLabel
       attribute:NSLayoutAttributeWidth
      multiplier:1.0f
        constant:0];

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