Swift

Swift is the iOS and macOS development language. With 1.5 billion active iPhones, iOS development remains one of the highest-paying mobile specializations: median iOS developer salary in the US is $148k. Swift 6.0 released in 2024 introduced strict concurrency checking, which is a major breaking change for existing codebases but produces dramatically more reliable async code. The emerging story: Swift is expanding beyond Apple platforms — Swift on Linux and Swift for WebAssembly are real projects with growing adoption. For anyone targeting the Apple ecosystem, Swift is mandatory.