Not a book, but since your description asks for a "source":
Developing iOS 8 Apps with Swift[0]: Stanford course with a great professor that focuses on learning Swift with a heavy focus on the iOS SDK. Really great for getting the fundamentals for iOS programming, and the course assumes a solid programming background (e.g., MVC).
Book:
Swift Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)[1]. This looks like it just came out, and I haven't read it, but I did read the authors' Obj. C Guide and their iOS Guide, and both were great, so I'm assuming the same for this one.
Developing iOS 8 Apps with Swift[0]: Stanford course with a great professor that focuses on learning Swift with a heavy focus on the iOS SDK. Really great for getting the fundamentals for iOS programming, and the course assumes a solid programming background (e.g., MVC).
Book: Swift Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)[1]. This looks like it just came out, and I haven't read it, but I did read the authors' Obj. C Guide and their iOS Guide, and both were great, so I'm assuming the same for this one.
0 - https://itunes.apple.com/us/course/developing-ios-8-apps-swi... 1 - http://www.amazon.com/Swift-Programming-Ranch-Guide-Guides/d...