UX Glossary · I
iOS
Apple's mobile operating system, and the platform conventions expected by everyone using an iPhone.
iOS is Apple’s operating system for iPhone, introduced in 2007 and named iPhone OS until 2010. iPadOS branched from it in 2019.
For a designer it is less an operating system than a set of expectations. Apple publishes the Human Interface Guidelines, which define navigation patterns, standard controls, typography and behaviour, and which App Store review partially enforces.
What is worth respecting
The conventions that carry real user habit: the back gesture from the left edge, the share sheet, the system date and time pickers, the tab bar at the bottom, pull to refresh, and Dynamic Type for users who have set a larger text size.
Overriding these is possible and usually a mistake. Jakob’s Law applies with unusual force on a phone, because your app occupies a few minutes of a day otherwise spent in other apps that all behave consistently.
Where the platforms genuinely differ
Beyond visual style: navigation models, the absence of a system back control, and Apple’s stricter privacy prompts, which affect onboarding flows that expect permissions to be granted.
In practice
For cross-platform work, share the information architecture and the content, and keep navigation and system controls native. Users do not evaluate your app against your other platform, they evaluate it against the phone in their hand.