From Apple: Xcode 7 + Swift 2

Download Xcode 7 and get started with Swift 2.0. Use the migrator in Xcode 7 to convert your existing your existing Swift code to use the new Swift 2.0 features and syntax.

• View latest beta releases of Xcode 7
• Swift Standard Library.playground
• Crustacean.playground
• The Swift Programming Language
• Swift Standard Library Reference
• Start Developing iOS Apps (Swift)
• Using Swift with Cocoa and Objective-C
• DemoBots: Building a Cross Platform Game with SpriteKit and GameplayKit
• Lister: A Productivity App Built in Swift

To which I add:

• Swift 2.0 Docs at SwiftDoc
• Swift Language Forum
• Swift Playgrounds Forum
• What’s New in Swift video
• Improving Your Existing Apps with Swift video
• Swift and Objective-C Interoperability video
• What’s New in LLDB video
• Authoring Rich Playgrounds video
• Protocol Oriented Programming in Swift video
• Apple’s Swift 2.0 Blog Announcement
• WWDC 2015 Sample Code