ios - 自动布局而不是 autoresizingMask

Question

如何在 UIView 子类中使用 NSLayoutConstraints(或 anchor )编写以下代码？

func commonInit() {
    aView                  = UIView()
    aView.autoresizingMask = [.flexibleHeight, .flexibleWidth]

    addSubview(aView)
}

override func layoutSubviews() {
    super.layoutSubviews()

    let smallerSide = min(bounds.width, bounds.height)

    aView.bounds = CGRect(x: 0.0, y: 0.0, width: smallerSide, height: smallerSide)
    aView.center = CGPoint(x: bounds.midX, y: bounds.midY)
}

一个目标是避免使用layoutSubviews()。此外，aView 必须保持 1:1 的纵横比。如果您需要更多信息，请告诉我。

PS:请让我们使用swift3，谢谢。

Answer 1

检查下面的代码:

let view = UIView(frame: CGRectZero)
    view.setTranslatesAutoresizingMaskIntoConstraints(false)
    super.init(frame: frame)
    let viewsDict = ["view": view]
    addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[view]-0-|", options: .allZeros, metrics: nil, views: viewsDict))
    addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[view]-0-|", options: .allZeros, metrics: nil, views: viewsDict))
    addSubview(view)