Yes, okay, I suppose you could go rummaging around the in the scattered and inconstant Xcode documentation to understand the rapidly evolving standards of source code markup in Xcode. But why would you? This book tis practical, through, and concise, and tells you eerything you need to know in a straightforward way. Worth it.

I got started with “Swift Documentation” using the article with that title on NSHipster. This “book" covers the material there in a little more detail: my favorite feature is the assessing of how Apple has used each feature, in their own documentation. I plan to use this book as a reference until the documentation flows from me in such a way that the reference is unneeded. My only quibble is that it would be easier to learn this material from as a playground, instead of an iBook.