WWDC2014: Apple introduced Swift
Swift is a new programming language for Cocoa and Cocoa Touch that has been created as a successor for Objective-C; nevertheless, developers can use both Swift and Objective-C in the same project.
Here is a list of available resources:
"The Swift Programming Language" is THE reference iBook Apple released on day 1.
Various sessions (from beginner to advanced levels) were run during WWDC14.
Currently under NDA.