Changes

* [[The Basics of Modern Objective-C]]* [[An Introduction to Auto Layout in iOS 6]]* [[Working with iOS 6 Auto Layout Constraints in Interface Builder]]* [[An iPhone iOS 6 Auto Layout Example]]* [[Implementing iOS 6 Auto Layout Constraints in Code]]* [[Implementing Cross-Hierarchy Auto Layout Constraints in iOS 6]]* [[Understanding the iOS 6 Auto Layout Visual Format Language]]* [[An Overview of iOS 6 Collection View and Flow Layout]]* [[An iPhone iOS 6 Storyboard-based Collection View Tutorial]]* [[Subclassing and Extending the iOS 6 Collection View Flow Layout]]* [[An Overview of iOS 6 Application State Preservation and Restoration]]* [[An iOS 6 iPhone State Preservation and Restoration Tutorial]]* [[Integrating Maps into iPhone iOS 6 Applications using MKMapItem]]* [[An Example iOS 6 iPhone MKMapItem Application]]* [[Using iOS 6 Event Kit to Create Date and Location Based Reminders]]* [[Integrating Twitter and Facebook into iPhone iOS 6 Applications]]* [[An iPhone iOS 6 Facebook Integration Tutorial using UIActivityViewController]]* [[iPhone iOS 6 Facebook and Twitter Integration using SLRequest]]* [[Making Store Purchases with the SKStoreProductViewController Class]]* [[Building In-App Purchasing into iPhone iOS 6 Applications]]* [[Preparing an iOS 6 Application for In-App Purchases]]* [[An iPhone iOS 6 In-App Purchase Tutorial]]* [[Configuring and Creating App Store Hosted Content for iOS 6 In-App Purchases]]