SimpleAnchor.swift

func pureLayout() {
    box.autoPinEdge(toSuperviewEdge: .top, withInset: 50)
    box.autoPinEdge(toSuperviewEdge: .left, withInset: 20)
    box.autoSetDimensions(to: CGSize(width: 100, height: 100))

    circle.autoPinEdge(.top, to: .top, of: box)
    circle.autoPinEdge(toSuperviewEdge: .right, withInset: 20)
    circle.autoSetDimensions(to: CGSize(width: 100, height: 100))

    longer.autoPinEdge(toSuperviewEdge: .left, withInset: 20)
    longer.autoPinEdge(toSuperviewEdge: .right, withInset: 20)
    longer.autoPinEdge(.top, to: .bottom, of: box, withOffset: 40)
    longer.autoSetDimension(.height, toSize: 40)
}

func anchorLayout() {
    box.translatesAutoresizingMaskIntoConstraints = false
    circle.translatesAutoresizingMaskIntoConstraints = false
    longer.translatesAutoresizingMaskIntoConstraints = false

    box.topAnchor.constraint(equalTo: view.topAnchor, constant: 50).isActive = true
    box.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 20).isActive = true
    box.widthAnchor.constraint(equalToConstant: 100).isActive = true
    box.heightAnchor.constraint(equalToConstant: 100).isActive = true

    circle.topAnchor.constraint(equalTo: box.topAnchor).isActive = true
    circle.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -20).isActive = true
    circle.widthAnchor.constraint(equalToConstant: 100).isActive = true
    circle.heightAnchor.constraint(equalToConstant: 100).isActive = true

    longer.topAnchor.constraint(equalTo: box.bottomAnchor, constant: 40).isActive = true
    longer.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 20).isActive = true
    longer.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -20).isActive = true
    longer.heightAnchor.constraint(equalToConstant: 40).isActive = true
}