GameKit Integrate Game Center services into iOS 26+ games using GameKit and Swift 6.3: authentication, leaderboards, achievements, multiplayer matchmaking, access point, dashboard, challenges, and saved games. Keep SpriteKit rendering, SceneKit 3D, TabletopKit board logic, and full SharePlay group-activity design in their framework domains; use GameKit only for Game Center handoff points. Contents - Authentication - Access Point - Dashboard - Leaderboards - Achievements - Real-Time Multiplayer - Turn-Based Multiplayer - Common Mistakes - Review Checklist - References Authentication All GameKi…