First, I don't think there's any restrictions on using Helvetica Neue so feel free to use that in you app for whatever you need. San Francisco font doesn't show up when enumerating installed fonts so you can't "pick" it in the usual sense. If you use the UIFont systemFont APIs, and San Francisco is the system font, it will be used automatically and you don't need to install anything. In fact, Apple prohibits installing SF font in your app. And if the system font is Helvetica Neue (which was standard before SF font), you will get that automatically by using systemFont APIs. So that's the correct way to handle this situation. systemFont will pick Helvetica Neue when it is system font on old systems, and SF on newer systems. Doug Hill https://github.com/djfitz/SFFontFeatures/graphs/traffic

Use the UIFont.systemFont APIs in your application and you will be using San Francisco font. No fonts need to be installed.

I did some research and managed to figure out much of the special typographic features mentioned in the WWDC talk, as well as a few others. I've documented the ones found here: https://github.com/djfitz/SFFontFeatures Here is a list of features that I support with my library: Straight-sided six and nine Open Four Vertically Centered Colon High Legibility One Story a Upper Case Small Capitals Lower Case Small Capitals Contextual Fractional Forms Monospaced/Proportional Numbers Superiors/Superscripts Inferiors/Subscripts Good luck! Doug Hill

I see that Apple has been locking down the San Francisco font for users to pick in a font menu. For example, I see in iOS 14 that SF font no longer shows up in a list of enumerated fonts. Unfortunately, you can't assume the systemFont APIs will return SF as the system font has already changed twice in my memory (Helvetica -> Helvetica Neue -> San Francisco). But it will likely not change anytime soon it's probably a good bet system font will be SF. Also, has been noted many times, it's appears legally murky to install the SF font in your app. My suggestion is to keep using system font and check font attributes for supported features you might require. Doug Hill https://github.com/djfitz/SFFontFeatures

The solution Apple recommends is to use the System font in your app. You can easily do this by using system font APIs. See for example UIFont.systemFont(ofSize:) - https://developer.apple.com/documentation/uikit/uifont This allows your application to work correctly on all iOS versions you support. Apple has said that the vertical metrics for the system font won't change, so the text in your app will layout correctly in all cases. You will get San Francisco font on versions of iOS that support it, and will (likely) use Helvetica Neue on older systems. And when your app runs with San Francisco as the system font, there are a lot of real cool typographic effects you get for free (e.g. vertically centered colon). Really, San Francisco is a great application font. Doug Hill https://github.com/djfitz/SFFontFeatures

I think you might need to be more specific. If you're creating an app for a non-Apple device, then you can't use San Francisco font. However, if you're creating an app on an Apple device (e.g. iPhone, iPad, Apple Watch, Apple TV), then use the System font and it will use San Francisco font. Also, when you use the system font APIs, it will automatically pick the correct Text or Display versions (technically "optical size variants") depending on the font size used. See also UIFont.preferredFont(forTextStyle style:) - https://developer.apple.com/documentation/uikit/uifont/1619030-preferredfont UIFont.systemFont(ofSize:) - https://developer.apple.com/documentation/uikit/uifont/1619042-systemfont Hope this answers your question. Doug Hill https://github.com/djfitz/SFFontFeatures