subviewB.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(subviewB)
constraints.append(NSLayoutConstraint(item: subviewB, attribute: .top, relatedBy: .equal,
                                      toItem: view, attribute: .top, multiplier: 1.0, constant: 150))
// subviewA.top = 1.0 * view.top + 150
constraints.append(NSLayoutConstraint(item: subviewB, attribute: .bottom, relatedBy: .equal,
                                      toItem: view, attribute: .bottom, multiplier: 1.0, constant: -150))
// subviewA.bottom = 1.0 * view.bottom - 150
constraints.append(NSLayoutConstraint(item: subviewB, attribute: .left, relatedBy: .equal,
                                      toItem: view, attribute: .left, multiplier: 1.0, constant: 100))
// subviewA.left = 1.0 * view.left + 100
constraints.append(NSLayoutConstraint(item: subviewB, attribute: .right, relatedBy: .equal,
                                      toItem: view, attribute: .right, multiplier: 1.0, constant: -100))
// subviewA.right = 1.0 * view.right - 100