San Francisco (sans-serif typeface) and iOS 10 is a new variant named "SF Compact Rounded". It is used in the new contact placeholder icons introduced in the OSes. The "SF Serif" variant was showcased during the keynote at WWDC 2018 on June 4, 2018 when the all-new Apple Books app was introduced. This variant is exclusive to Apple Books in iOS 12 and macOS Mojave, is not mentioned in Apple's Typography design guidelines, and is not publicly downloadable like other variants of the San Francisco typeface. Since its introduction, San Francisco has gradually replaced most of Apple's other typefaces on their software and hardware
Helvetica Nimbus Sans. This is an extremely large font family with optical sizes spaced for different sizes of text and other variants such as stencil styles. Florian Hardwig has described its display-oriented styles, with tight spacing, as more reminiscent of Helvetica as used in the 1970s from cold type than any official Helvetica digitisation. Monotype's Arial, created for IBM and also used by Microsoft, is indistinguishable by most non-specialists. Matthew Carter, who was a consultant for IBM during its design process, describes it as "a Helvetica clone, based ostensibly on their Grots 215 and 216" (Monotype's old 1920s sans-serif family, popular