A CoreAnimation developer designs and implements visual effects and animations for applications on Apple platforms like iOS, macOS, watchOS, and tvOS. They utilize Apple's Core Animation framework to create smooth, efficient, and visually appealing interfaces. Their duties include developing complex animation systems, optimizing performance and resource usage, troubleshooting visual issues, and collaborating with designers and other developers to ensure a seamless user experience. They also maintain and improve existing animations, and stay updated on the latest trends and technologies in animation development. They often work in teams, contributing to the overall aesthetic and functionality of an application.