ScrollWithSurpriseAnchor.swift

func pureLayout() {
    scrollView.autoPinEdgesToSuperviewEdges(with: .zero)
    scrollView.autoPinEdge(.bottom, to: .bottom, of: longer, withOffset: 20)

    box.autoPinEdge(toSuperviewEdge: .top, withInset: 150)
    box.autoAlignAxis(toSuperviewAxis: .vertical)
    box.autoSetDimensions(to: CGSize(width: 100, height: 100))

    circle.autoPinEdge(.bottom, to: .bottom, of: self.view, withOffset: -20, relation: .lessThanOrEqual)
    circle.autoPinEdge(.bottom, to: .top, of: longer, withOffset: -20, relation: .lessThanOrEqual)
    circle.autoAlignAxis(toSuperviewAxis: .vertical)
    circle.autoSetDimensions(to: CGSize(width: 100, height: 100))

    longer.autoPinEdge(.left, to: .left, of: self.view, withOffset: 20)
    longer.autoPinEdge(.right, to: .right, of: self.view, withOffset: -20)
    longer.autoPinEdge(.top, to: .bottom, of: box, withOffset: 660)
    longer.autoSetDimension(.height, toSize: 200)
}

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

    scrollView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
    scrollView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
    scrollView.bottomAnchor.constraint(equalTo: longer.bottomAnchor, constant: 20).isActive = true

    box.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 150).isActive = true
    box.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor).isActive = true
    box.widthAnchor.constraint(equalToConstant: 100).isActive = true
    box.heightAnchor.constraint(equalToConstant: 100).isActive = true

    circle.bottomAnchor.constraint(lessThanOrEqualTo: view.bottomAnchor, constant: -20).isActive = true
    circle.bottomAnchor.constraint(lessThanOrEqualTo: longer.topAnchor, constant: -20).isActive = true
    circle.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor).isActive = true
    circle.widthAnchor.constraint(equalToConstant: 100).isActive = true
    circle.heightAnchor.constraint(equalToConstant: 100).isActive = true

    longer.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 20).isActive = true
    longer.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -20).isActive = true
    longer.topAnchor.constraint(equalTo: box.bottomAnchor, constant: 660).isActive = true
    longer.heightAnchor.constraint(equalToConstant: 200).isActive = true
}