Every designer creating an app for the iPhone and any Apple device should have a good understanding of the Human Interface Guidelines, Apple’s essential information tool about the design of their platforms. There are other resources for designers, including videos, news and resources all available in the Developer Design section of Apple.com.

The Human Interface Guidelines are by their nature, guidelines. Apple refers to the documentation as guidance. What you will not find are strict styling rules from Apple, rather broad topics to help app designers create thoughtful experiences. There are some good but loosely held rules, and some important considerations core to Apple such as accessibility and privacy.

Apple is fully aware that an app needs to find its own voice and be true to the brand. Apple has invested in creating typefaces for their screens which are readily available to designers and developers—San Francisco sans-serif font, New York serif font and the SF Symbols icon library. At the same time, adding a custom font is easy and encouraged, with Apple’s only concern being legibility. Most font houses now licence their typefaces for app use.

SwiftUI doesn’t come with pre-made components, apart from lists, navigation and tabs, instead developers get the building blocks used to make their own components. This approach allows for more flexibility. Take for example many of the apps recognized with Apple Design Awards, apps such as Headspace, Flighty, Duolingo or iTranslate Converse break the mould to offer experiences outside the typical iOS layout. There are common underlying aspects of these apps—they leverage the mobile experience and use some of the visual language and technologies available with iOS.

Designing an app is a delicate balance, and it will depend on your audience. Early-adopters will be open to new approaches, while a mass-market ecommerce app may need to include more familiar interactions such as the tab bar. Almost every Apple app uses the tab bar, though some apps, such as Maps, provide a singular focus that makes tabs unnecessary.

Contrast the HIG with Google’s Material design and you have a much more prescriptive approach to app design styling. Material is customizable, but it’s also intended to be an equal foundation for Android apps.

Both platforms have set patterns of interaction and behaviour. Over the years we’ve seen the rise and fall of single experience apps creating a hybrid between iOS and Android, but these apps never pleased each platform’s customers. For example the hamburger menu never felt at home in an iOS app, and providing an iPhone app with a hamburger menu and no tabs may break too many conventions. Material even introduced a tab bar to the Android app space, suggesting the pattern held some value for both platforms.