如果我想以编程方式创建这些约束,我该怎么做?
答
你可以做到这一点比较用视觉语言的格式很简单:
添加您的看法,topLayoutGuide
和bottomLayoutGuide
到字典。我用views
。您还必须将translatesAutoresizingMaskIntoConstraints
设置为false
以使约束生效。
例子:
view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[yourView]-(-15)-|", options: [], metrics: nil, views: views))
view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[topLayout][yourView][botLayout]", options: [], metrics: nil, views: views))
答
一种方式做的是:
let newView = UIView()
newView.backgroundColor = UIColor.redColor()
newView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(newView)
let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0)
view.addConstraint(horizontalConstraint)
let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: -15)
view.addConstraint(verticalConstraint)
let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
view.addConstraint(widthConstraint)
let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0)
view.addConstraint(heightConstraint)
获取更多信息,您可以在这里遵循`NSLayoutConstraints`这个Swift | Adding constraints programmatically
见节 - > HTTPS:/ /developer.apple.com/library/ios/documentation/UserExperience/Conceptual/AutolayoutPG/ProgrammaticallyCreatingConstraints.html#//apple_ref/doc/uid/TP40010853-CH16-SW1 – Adrian