Swift Programming: The Big Nerd Ranch Guide

Through the authors' carefully constructed explanations and examples, you will develop an understanding of Swift grammar and the elements of effective Swift style.
  Throughout the book, the authors share their insights into Swift to ensure that you understand the hows and whys of Swift and can put that understanding to use in different contexts.
After working through the book, you will have the knowledge and confidence  to develop your own solutions to a wide range of programming challenges using Swift.