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 Book
"The Swift Programming Language" is THE reference iBook Apple released on day 1.
The Sessions
Various sessions (from beginner to advanced levels) were run during WWDC14.
Currently under NDA.
