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HomeiOS DevelopmentSwift wants a greater language reference – Ole Begemann

Swift wants a greater language reference – Ole Begemann

In August 2020, I posted a rant on the Swift boards concerning the poor state of Swift documentation. Nothing got here of it, however I need to reiterate one level I made then: the Swift mission sorely wants a searchable, linkable language reference.

To be honest, Swift does have a language reference: the eponymous part in The Swift Programming Language (TSPL) incorporates many of the data I’d count on from such a useful resource. However that part isn’t properly structured to function an precise reference:

TSPL just isn’t searchable

The TSPL web site doesn’t have a search area. Even when it had one, I think about it could be a full-text search over your complete web site, as is widespread (and acceptable) for a e book. A language reference wants a unique search engine:

  • Trying to find key phrases (if, case, the place) should reliably discover the documentation for the key phrase as the highest consequence. I don’t need to see the lots of of pages that comprise the phrase “if” of their physique textual content.

  • I’d love to have the ability to seek for punctuation. Think about if you happen to may seek for a logo similar to # and it could present you a listing of all syntax parts that use this image. This may be very informative and an effective way to discover the language, not only for inexperienced persons — particularly with good IDE integration (see under). Swift is such a giant and sophisticated language that most individuals gained’t know each language characteristic.

A language reference wants a search engine that is aware of to deal with key phrases and punctuation.

TSPL just isn’t linkable

Pages in TSPL are typically lengthy, with many separate gadgets crammed right into a single web page. For instance, all compiler attributes are documented on a single web page.

Sharing a hyperlink to a particular attribute, similar to @resultBuilder, is troublesome if you already know your method round HTML and just about not possible if you happen to don’t (to not point out the dangerous URL).

As a reader, opening such a hyperlink is disorienting because it drops you in the midst of a really lengthy web page, 95 % of which is irrelevant to you.

The reader expertise is even poorer while you arrive from a search engine (as most individuals would as a result of the location has no search operate): TSPL is without doubt one of the high outcomes for swift resultbuilder on Google, however it drops you on the high of the superlong web page on Attributes, with no indication the place to search out the data you’re on the lookout for.

Each language assemble, key phrase, attribute, and compiler directive ought to have its personal, linkable web page.

TSPL is structured improper

The Language Reference part in TSPL is organized as if it was written for parser or compiler builders. It makes use of the language’s grammar as a place to begin and branches out into expressions, statements, declarations, and so forth.

For instance:

I don’t learn about you, however as a person of the language, that’s not how I take into consideration Swift or how I seek for documentation.

Along with an excellent search engine, a language reference wants an alphabetical index of each key phrase or different syntax ingredient, with hyperlinks to the respective element web page.

IDE integration

I used to be cautious to make this a criticism concerning the documentation for Swift and never concerning the (equally poor) state of Apple’s developer documentation. Swift just isn’t restricted to app growth for Apple units, and I consider it’s important for Swift to place itself as a standalone mission if it needs to be perceived as a viable general-purpose language.

It’s good that TSPL is hosted on and never, and that’s additionally the place this new language reference I’m envisioning ought to reside. (I additionally assume it’s improper to host the Swift API documentation on

However as soon as we’ve got this language reference, Apple ought to after all combine it into Xcode for offline search and context-sensitive assist. Think about if you happen to may Possibility-click not solely identifiers however any token in a supply file to see its documentation.

Just a few examples:

  • Clicking on if case let would clarify the sample matching syntax.
  • Clicking on in would explains the assorted closure expression syntax variants.
  • Clicking on #fileID would present you an instance of the ensuing string and evaluate it to #file and filePath.
  • Clicking on @propertyWrapper would clarify what a property wrapper is and how one can implement one.
  • Clicking on @dynamicMemberLookup would clarify its goal and what you need to do to implement it.
  • Clicking on < in a generic declaration would clarify what generic parameters are and the way they’re used.
  • Clicking on ? would present all language parts that use a query mark (shorthand for Optionals, non-obligatory chaining, Non-obligatory sample matching, strive?).
  • Clicking on /// would checklist the magic phrases Xcode understands in doc feedback.

You get the concept. This may be such a giant assist, not just for inexperienced persons.

To summarize, that is the unhappy state of looking for language options in Xcode’s documentation viewer:

Xcode documentation viewer showing meaningless results when searching for 'guard'
guardian let me watch youtube else { throw match }

Xcode documentation viewer showing meaningless results when searching for 'associatedtype'
Nope, this isn’t what I used to be on the lookout for.

And this mockup reveals the way it could possibly be:

Mockup of an imagined Xcode documentation popover for #fileID
Sure, I rebuilt Xcode’s documentation popover in SwiftUI for this mockup, syntax highlighting and all.


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