There is a custom font San Francisco, designed by Apple as the system font for iOS, tvOS, watchOS, and macOS. The font is very legible on whichever Apple system or display you are viewing on. As a developer or designer, you are going to enjoy having access to this font for things like mockups and other related works.
If you don’t have the San Francisco font on your Mac computer. You will be glad to learn that Apple has availed it as a free download for all; of course to those installing it on Apple devices.
Downloading and Installing San Francisco fonts
Go to the Apple Developer Fonts page and select the San Francisco font pack. Next, you will need to mount the DMG file you have downloaded and then access the disk image using the Finder.
At this stage, you should be presented with the font limited license files elaborating on the usage limitation. Most of the nitty gritty here are meant for developers, but as a general user, you may want to be acquainted with them so you know the limitations.
Next, select each individual fonts folder and select all (press Command + A) on the keyboard and then open (Command + O) to load them into the font manager.
Now click on ‘Install Font’ on all the available font installer windows that will be presented to you. Repeat the process with all the other fonts (individually) in the folder mounted disk image.
The Font Book should now open showing the User installed fonts that now include the SF Pro and SF Compact.
Going forward, you can access the San Francisco font pack as you would any other font available on your Mac computer. That is by using the appropriate text styling modification menu.
Though you should put in mind that SF Compact font was designed for watchOS, while the SF Pro was designed for macOS, iOS, and tvOS.