public static FluentLayout Above(this UIView view, UIView previous, nfloat?margin = null) => view.Bottom().EqualTo().TopOf(previous).Minus(margin.GetValueOrDefault(DefaultMargin));
public static FluentLayout WithSameBottom(this UIView view, UIView previous) => view.Bottom().EqualTo().BottomOf(previous);
public static FluentLayout AtBottomOf(this UIView view, UIView parentView, nfloat?margin = null) => view.Bottom().EqualTo().BottomOf(parentView).Minus(margin.GetValueOrDefault(DefaultMargin));