Xcode is Apple’s integrated development environment (IDE) for building software across all of its platforms: macOS, iOS, iPadOS, watchOS, tvOS, and visionOS. Apple’s own developer site describes Xcode as the toolset developers use to “design, develop, and distribute” apps, combining a source editor, project management, a debugger, performance instruments, and the simulators and SDKs needed to target each platform inside a single application.
Xcode grew out of an earlier Apple tool called Project Builder, which had its roots in the NeXTSTEP developer tools that Apple inherited when it acquired NeXT in 1996. Xcode 1.0 shipped in 2003 alongside Mac OS X v10.3 “Panther,” replacing Project Builder with a reworked interface while keeping the same lineage of build tooling. Over subsequent releases Apple folded more of the development workflow into the one application.
A defining piece of Xcode is Interface Builder, the visual layout tool (also inherited from NeXTSTEP) used to construct graphical user interfaces by arranging views and wiring them to code. Originally a separate application, Interface Builder was integrated directly into Xcode beginning with Xcode 4 in 2011, so that designing a UI and editing its backing code happened in the same window.
Xcode also bundles the iOS Simulator, which lets developers run and test iPhone and iPad apps on the Mac without physical hardware, and the Instruments performance and profiling suite. The first iPhone-capable version of these tools arrived with the iPhone SDK in 2008, giving third-party developers their first official path to writing native iOS applications.
Underneath the editor, modern Xcode compiles code with the LLVM compiler infrastructure and its Clang front end. Apple was a major sponsor of LLVM, hiring its creator Chris Lattner, and shifted its toolchain from GCC to Clang/LLVM over the late 2000s and early 2010s. That same toolchain later became the foundation for the Swift programming language, which Apple introduced in 2014 and built directly into Xcode alongside the older Objective-C support.