Best Swift Open Source Repositories

Swift is a statically typed, compiled language Apple introduced in 2014 as the intended successor to Objective-C for building applications across macOS, iOS, watchOS, and tvOS. It combines memory safety features, including optionals that force developers to explicitly handle the possibility of a missing value at compile time, with performance close to C, achieved partly through automatic reference counting rather than a traditional garbage collector. Its syntax is considerably more concise and modern than Objective-C's, while still interoperating with existing Objective-C code and C libraries through bridging.

Swift is used almost exclusively for Apple platform development: native iOS and macOS applications, and increasingly server-side software through frameworks like Vapor, though that use case remains a much smaller part of Swift's overall footprint compared to mobile and desktop apps. Since going open source in 2015, Swift has also gained some traction on Linux, though the vast majority of Swift code in the wild still targets Apple's own platforms and APIs.

Given Swift's tight coupling to Apple's ecosystem, it appears in open-source repos with native iOS or macOS clients. Immich, Ente, and AFFiNE all use Swift for their native iOS applications, giving users a fully native mobile experience alongside their cross-platform backends. Expo and Compose Multiplatform include Swift in their native iOS integration layers, and OBS Studio uses Swift for parts of its macOS-specific interface and system integration code, alongside its older Objective-C components.