Yesterday, I wrote that books should get you to write code, not just read it. I’ve been working on a companion to Apple’s Swift Programming Language book that helps you do that by offering exercises for each chapter.
I just published the companion to the Methods chapter on App-o-Mat. If you want to start from the beginning, go to the outline of Section 1. If you understand the content of the corresponding chapter, the exercises are meant to be very easy. If you are having trouble with them, it would be a good idea to review the chapter again before moving on.