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 2010 when Apple rebranded it to iOS. In 2019, Apple began to use the iPadOS moniker to brand the version of the operating system that is 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 similar to 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. As of 2017, iOS has only been compiled for ARM-based processors and only runs on the iOS platforms that Apple manufactures.

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.

iPhone OS 1.0 through iOS 10 was 32 and 64-bit compatible. iOS 11 dropped any support for 32-bit ARM processors and corresponding binaries and was the first version of iOS with only 64-bit support. iOS 7 was the first version of iOS to bring 64-bit support.

No official emulators exist that can run the retail version of iOS, however, Apple does provide 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.