Traditionally full support for "complex scripts" like Devanagari in MacOS and iOS has required the use of special AAT fonts supplied by Apple. The much more common OpenType fonts for such languages used by other platforms would not work right.
While I have not seen anything directly from Apple, typography experts tell me that the Core Text API of Sierra and iOS 10 now supports the specs of the Universal Shaping Engine (USE). The result should be that Apple devices can use a much wider variety of OpenType fonts for the large number of languages which use these scripts. For more info on the USE, see
Making Fonts for the USE
Creating and Supporting OpenType fonts for the USE
While I have not seen anything directly from Apple, typography experts tell me that the Core Text API of Sierra and iOS 10 now supports the specs of the Universal Shaping Engine (USE). The result should be that Apple devices can use a much wider variety of OpenType fonts for the large number of languages which use these scripts. For more info on the USE, see
Making Fonts for the USE
Creating and Supporting OpenType fonts for the USE
