程序化自动布局约束到Superview的边缘 [英] Programmatic Auto Layout Constraints to Edges of Superview

问题描述

我已经在Xcode的故事板编辑器中完成了很多自动布局，但是我很少在代码中做任何事情.在一个特定的实例中，我需要创建与这些约束等效的程序设计:

I have done quite a bit of auto layout in Xcode's storyboard editor, but I rarely ever do anything in code. In one particular instance, I need to create the programmatic equivalent to these constraints:

这些约束已添加到 textView 中，而超级视图是另一个名为 commentBox 的视图.到目前为止，我已经尝试过了，但是代码感到多余，并导致约束冲突的自动布局错误:

These constraints are added to textView and the superview is another view called commentBox. I've tried this so far, but the code feels redundant and results in an auto layout error of conflicting constraints:

//Trailing
textView.addConstraint(NSLayoutConstraint(item: textView, attribute: .trailing, relatedBy: .equal, toItem: cell.commentBox, attribute: .trailing, multiplier: 1, constant: 15))
//Leading
textView.addConstraint(NSLayoutConstraint(item: textView, attribute: .leading, relatedBy: .equal, toItem: cell.commentBox, attribute: .leading, multiplier: 1, constant: 15))
//Bottom
textView.addConstraint(NSLayoutConstraint(item: textView, attribute: .bottom, relatedBy: .equal, toItem: cell.commentBox, attribute: .bottom, multiplier: 1, constant: 10))
//Top
textView.addConstraint(NSLayoutConstraint(item: textView, attribute: .top, relatedBy: .equal, toItem: cell.commentBox, attribute: .top, multiplier: 1, constant: 10))

知道我在做什么错吗?谢谢！

Any idea what am I doing wrong? Thanks!

推荐答案

尝试一下:

commentBox.addSubview(textView)

textView.translatesAutoresizingMaskIntoConstraints = false

textView.topAnchor.constraint(equalTo: commentBox.topAnchor, constant: 10).isActive = true
textView.bottomAnchor.constraint(equalTo: commentBox.bottomAnchor, constant: -10).isActive = true
textView.leadingAnchor.constraint(equalTo: commentBox.leadingAnchor, constant: 15).isActive = true
textView.trailingAnchor.constraint(equalTo: commentBox.trailingAnchor, constant: -15).isActive = true

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