Add support for an offline reading experience (ePUB, PDF, etc.)

[krilnon]

The shipping book supports an offline reading experience with an ePUB version available on swift.org and on Apple Books. We should evaluate which formats we want to support going forward, and where in the publication pipeline we generate these artifacts.

Blocked by: swiftlang/swift-docc#354

rdar://71373710

[Gerzer]

I personally love that TSPL is available in the Apple Books store. It would be great if that availability can continue with this new publication pipeline!

[amartini51]

See also swiftlang/swift-docc#354, which likely requires much of the same underlying work in DocC.

[schwa]

A PDF of the TSPL book is almost required at this point. Losing the ability to download the TSPL seems like a major lose of usability and functionality.

[7ombie]

I had a couple of technical issues reading the book offline.

On the (11th-gen) Kindle Paperwhite (with an eInk display), the code examples (including inline code) use the same (variable width) font as the rest of the text.

In Apple Books, the syntax highlighting only works when the page is light. In Dark Mode, the code is all the same color. I'm not sure if this is a limitation of the software or an oversight with the formatting.

@schwa - The issue with PDFs is that you cannot resize them for tablets, ebook readers or people with poor eyesight. They only really work on desktops, where EPUB (and Apple Books) still makes more sense, at least generally.

[amartini51]

@7ombie Thanks for this feedback about the ePUB. However, that file was build using the legacy pre-DocC pipeline, which TSPL is no longer using. (That's why there's no longer an ePUB version of TSPL available.) When we investigate adding ePUB support to DocC, we can watch for these issues in case any of them re-occur.

[adamhill]

Any timeframe for EPUB / PDF output?

If this is going to take a while, can a static HTML site be generated by DocC that would be compatible with tablets / desktops?

How close is the current site that is generated able to be moved around as a ZIP archive and un-zipped on another computer for use?

Massive thanks to all the contributors for the work into DocC'ing the Swift Language spec!