How do I use the single story 'a' as used in Apple Notes?

In Apple Notes for iOS and MacOS, Apple uses a single-story variant of the lowercase a. It is only used in Notes and Reminders far as I can tell, though it is still the San Francisco font. I am curious how this is accomplished as I can't seem to find it anywhere in the documentation.


I prefer guideance in Objective-C.


Thanks,.