ios - 使用自动布局，但代价是没有框架

Question

我有一个在没有框架的情况下启动的盒子，因此它的中心和大小为 0。

let blackBox = UIView()
blackBox.backgroundColor = .blackColor()
blackBox.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(blackBox)
view.addConstraint(NSLayoutConstraint(item: blackBox, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .Width, multiplier: 0.1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blackBox, attribute: .Height, relatedBy: .Equal, toItem: view, attribute: .Height, multiplier: 0.5, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blackBox, attribute: .CenterX, relatedBy: .Equal, toItem: view, attribute: .CenterX, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blackBox, attribute: .CenterY, relatedBy: .Equal, toItem: view, attribute: .CenterY, multiplier: 1, constant: 0))

无论如何，是否可以使用自动布局将居中 subview 插入blackBox 而不，或者是否有一种更简洁的方式我可以/应该使用它。我能看到这种情况发生的唯一方法是:

let blueBox = UIView()
blackBox.addSubview(blueBox)
blueBox.translatesAutoresizingMaskIntoConstraints = false
blueBox.backgroundColor = UIColor.blueColor()
view.addConstraint(NSLayoutConstraint(item: blueBox, attribute: .CenterX, relatedBy: .Equal, toItem: blackBox, attribute: .CenterX, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blueBox, attribute: .CenterY, relatedBy: .Equal, toItem: blackBox, attribute: .CenterY, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blueBox, attribute: .Width, relatedBy: .Equal, toItem: blackBox, attribute: .Width, multiplier: 0.4, constant: 0))
view.addConstraint(NSLayoutConstraint(item: blueBox, attribute: .Height, relatedBy: .Equal, toItem: blackBox, attribute: .Height, multiplier: 0.4, constant: 0))

Answer 1

我个人会使用var bluebox = UIView(frame: CGRECT)并相应地设置CGRect。