Pin an edge of a view to *another* edge of its superview's safe area?

[denjiz]

Is it possible to pin one edge of a view (e.g. .top) to another edge of its superview's safe area (e.g. .bottom)?. I'd like to accomplish this behavior:
someView.topAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.bottomAnchor, constant: -50)

From what I see in the PureLayout API, currently it's possible to pin only to the same edge of the superview's safe area.

[toohotz]

A bit late to replying as for some reason I do not get Github notifications but I can see the use case for this with the UILayoutGuide introduced in iOS 11.

Would make a good case to replace the deprecated - (NSLayoutConstraint *)autoPinToTopLayoutGuideOfViewController:(UIViewController *)viewController withInset:(CGFloat)inset related methods in the codebase.