public static void AddAttributes(this NativeNSMutableAttributedString s, NativeCTStringAttributes a, StringRange r)
{
s.AddAttributes(a, new NSRange(r.Location, r.Length));
}
public void AddAttributes(IRichTextAttributes styleClass, StringRange range)
{
var attrs = ((NativeStringAttributesWrapper)styleClass).Attributes;
s.AddAttributes(attrs, new NSRange(range.Location, range.Length));
}