First impressions of SwiftUI

Last updated 31 days ago by Matt Gallagher

swift

A little over a month ago, I released CwlViews and then followed up with an article suggesting that Apple might be about to release their own declarative views library. At WWDC this week, they did just that, releasing SwiftUI.

This article will look at how SwiftUI’s approach to declarative views compares to CwlViews, why the two approaches differ and what Apple changed to make this possible. I’ll end with some thoughts about how this will affect macOS and iOS development.

Everyone and no-one saw this coming

Hooray, I predicted a thing. But I still managed to be surprised.

Apple did, as rumors suggested over a year ago, introduce a declarative views library. I correctly surmised that Interface Builder XML would be replaced by Swift code. I didn’t include my prediction that numerous recent Swift evolution proposals might herald integration with this library but that too was apparent.

However, I had expected the library to be a layer on top of AppKit/UIKit so almost everything else about SwiftUI took me by surprise. I mean, you don’t just casually replace frameworks with a 30 year history.

Of course, Apple didn’t do this on a whim and it appears that parts of SwiftUI have been in development for 7-10 years (yes, multiple Swift components released at WWDC this year predate Swift). A huge number of components (across platforms, Xcode, toolchains) have been developed to support the effort. It’s possible that hundreds of developers have been involved with an effort of this scale.

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