Question

我这样设置UIView的宽度：

subscribe(onNext:

现在我要更改宽度。问题是：如何删除旧约束并添加新约束？我确实这样创建了contentView.widthAnchor.constraint(equalToConstant: CGFloat(scrollWidth())).isActive = true

NSLayoutConstraint

如何为scrollWidthConstraint = NSLayoutConstraint( item: contentView, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: CGFloat(scrollWidth()) )设置该约束以便以后更改？

Answer 1

首先更好地使用它，并简短地为其指定一个引用

var widCon:NSLayoutConstraint! 

widCon = contentView.widthAnchor.constraint(equalToConstant: CGFloat(scrollWidth()))
widCon.isActive = true

代替NSLayoutConstraint(item: contentView,，然后将其更改为常量

widCon.constant = ////

更改视图宽度约束

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