An Apple Swift developer designs, develops, and maintains iOS applications using the Swift programming language. They collaborate with cross-functional teams to define, design, and ship new features, ensuring the performance, quality, and responsiveness of applications. They also identify and correct bottlenecks and fix bugs, maintaining code quality, organization, and automatization. Their work includes understanding end-user requirements, translating them into effective code, and integrating various elements of the application. Additionally, they may also be involved in user interface design, testing, and deployment, thus playing a crucial role in the entire app development cycle.