A GameCenter developer is responsible for integrating Apple's GameCenter into iOS games to enable social gaming features. They utilize the GameKit framework to add leaderboards, achievements, multiplayer functionality, and allow players to challenge friends. They ensure seamless game experience across all Apple devices and manage user's game progress. Their work also involves troubleshooting and resolving issues related to GameCenter integration. They work closely with other developers, designers, and stakeholders to create engaging and interactive gaming experiences. They also ensure that the games comply with Apple's guidelines and privacy policies. Their role is crucial in enhancing the overall user experience.