How to create a subscript with NSAttributedString

Question

I see for NSAttributedString has a specific attribute for superscript, but I can't find one for subscript. What is the general practice for using NSAttributedString to create a subscript character?

Example: H2O

Answer 1

Try NSSuperscriptAttributeName with a negative value.

Failing that, the hard way would be to replace [0123456789] characters with [₀₁₂₃₄₅₆₇₈₉] in the string.