IOS

iOS is a series of mobile operating systems developed by Apple for their mobile device platforms (iPhone, iPod, and iPad). It was originally or formerly called iPhone OS and introduced alongside the 1st generation iPhone. The name stayed until the release of the iPad in early 2010 when Apple rebranded it to iOS. In 2019, Apple began to use the iPadOS moniker to brand the version of the operating system used on iPad devices.

iOS is based on the codebase of macOS, formerly OS X, and shares the same kernel, filesystem, and binary formats. The userland of iOS is like that of macOS, but with a mobile-friendly design that is touchscreen and content-centric. iOS lacks direct access to the filesystem and is unable to run arbitrary code by default. The only distribution method for software officially allowed on iOS is the built-in App Store.

iOS's userland consists of a home screen (known as Springboard) that manages the user's applications. Many applications from macOS exist in iOS and vice-versa.

Since the release of iOS 11 in 2017, iOS has only been compiled for 64-bit ARM-based processors. Since the release of iOS 16 in 2022, iOS has only been compiled for iPhone models.

No official emulator that can run the retail version of iOS exists. However, Apple provides the iOS Simulator, which runs a modified build of iOS on top of macOS with output in a dedicated window. Unofficial emulators like Corellium and QEMU-T8030 can emulate iOS to an extent. There is also an open source fork of QEMU that can emulate a 1st generation iPod touch on iPhone OS 1.1.