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by Brian Schrader

Swift Dynamism

Posted on Mon, 30 May 2016 at 08:53 PM

There's been a lot of talk lately about Swift's relationship with dynamic runtime features. Since I've been developing in Swift for almost two months, I'm perfectly qualified to comment on it in depth, and that's what I'm now going to do (sorry).

First off, I like Swift's syntax a lot. Trailing closures are a thing I didn't know I needed, and while I have a few nitpicks about the language, overall I'm really enjoying using it.1 That said, I've found myself adopting a few strange habits when writing Swift that I'm not sure are good best practices, but they do seem to be the way that Apple wants Swift to be written. The biggest offender, and my least favorite feature: switch-case statements.

Brent Simmons:

[In the old days] There were lots of switch statements. To add, for instance, a copy (or whatever) implementation to a particular view, you’d have to edit your event dispatcher to know about that particular view and its copy function. Making changes required making changes in various places.

- Oldie Complains About the Old Old Ways

Swift's enums are very powerful, but Apple's sample code uses them for so many things.2 I've found myself switch-case-ing through enums in most of my ViewControllers. It not only looks ugly, but just feels wrong.

Gary Bernhardt:

Some apologists... [would say] that it's the programmer's fault for using it in this way... My own view is that the behavior that you see a tool being used for is the behavior that that tool encourages.

- The Birth and Death of Javascript (~3:30)

Brent, and many others, seem concerned about Swift's current relationship with dynamic features. While I don't dismiss the "old guy complaining about the new ways" effect, I never like to discount the opinions of long-time, seasoned platform developers. They've seen these kinds of things play out before. I haven't run into most of the other issues and concerns that Brent has brought up, but I have had to write more than a few switch-case statements, which is more than a few too many.


1 When Swift came out, it was a hardcore LBYL language. Now that it has try statements, the language feels confused. I don't know which is more "Swifty".
2 In Python, the community has strong opinions about what's "Pythonic". The way Apple recommends developers write Swift will have a huge influence on what becomes the "Swifty" style.
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