Chapter 1: Getting Started with Game Kit and Game Center Game Kit and Game Center a History Game Center Benefits and Marketing Game Kit: An Overview Sample Game: UFOs UFOs: Examining the Source Code Getting Started with iTunes Connect Chapter 2: Game Center: Setting Up and Getting Started Game Center from the user perspective Testing for Game Center Authenticating with Game Center The Sandbox Watching for Status Changes Working with GKLocalPlayer Retrieving a Friends List Friend List Avatars Working with Players Chapter 3: Leaderboards Why a Leaderboard? An Overview of Leaderboards in Game Center Configuring a Leaderboard in iTunes Connect Posting a Score Setting a Default Leaderboard Adding Score Posting to UFOs Handling Failures When Submitting a Score Presenting a Leaderboard Customizing the Leaderboard Mapping a Player ID Local Player Score A Better Approach Chapter 4: Achievements Why Achievements? An Overview of Achievements in Game Center Configuring Achievements in iTunes Connect Resetting Achievements Adding Achievement Hooks Chapter 5: Matchmaking and Invitations Why Add Matchmaking and Invitations to Your App? Common Matchmaking Scenarios Creating a New Match Request Presenting Match GUI Handling Incoming Invitations Auto-Matching Matching Programmatically Adding a Player to a Match iOS 5 Reinvites Player Groups Player Attributes Player Activity Using Your Own Server (Hosted Matches) Chapter 6: The Peer Picker Benefits of the Peer Picker Real-World Examples Working with Sessions Presenting a Peer Picker Advanced GKSession Interaction The Peer Picker Delegate Summary Chapter 7: Network Design Overview Three Types of Networks Less Common Networks Reliable Data vs. Unreliable Data Sending Only What Is Needed Prediction and Extrapolation Formatting Messages Preventing Cheating and Preventing Timeout-Related Disconnections What to Do When All Else Fails Chapter 8: Exchanging Data Modifying a Single-Player Game Setting Up Our Engine for Multiplayer Putting Everything Together Disconnections Chapter 9: Turned-Based Gaming with Game Center A New Sample Project GKTurnedBasedMatchmakerViewController Starting a New Game Making the First Move Continuing a Game in Progress Ending a Match Quitting and Forfeiting Programmatic Matches GKTurnBasedEventHandler Chapter 10: Voice Chat Voice Chat for Game Center Voice Chat for Game Kit Putting It Together Chapter 11: In-App Purchase with StoreKit Setting Up Your App in iTunes Connect Adding Products to Your App Purchasing a Product Subscriptions and Renewals Test Accounts and Testing Purchases Submitting a Purchase GUI Screenshot Developer Approval Receipts Tying Everything Together in UFOs.