I need to display text in a mixture of languages using the text-drawing functions in iOS. To make it concrete, let's say English and Malayalam. Malayalam (മലയാളം) is a beautifully curly language but hard to display right. It is usually best to use a specialist font which has been tuned to handle all its subtleties. So I might decide to use Caslon for English text, and Kartika for Malayalam.
Is there any way of telling iOS not only the font I want to use but the font it should fall back to, or am I reduced to analysing the text string, isolating "Malayalam-only" runs, and explicitly specifying Kartika for the Malayalam parts and Caslon for the English ones?
(Yes, I would of course license and embed Caslon and Kartika: this is not a question about font embedding but about font fallback specification).