What’s new in SwiftUI for iOS 17

This is another huge year of updates, delivering many highly requested features such as advanced scroll view effects, container relative sizing, and even Metal shaders.

Paul Hudson June 16th 2023 @twostraws

SwiftUI continues to evolve at a rapid pace, and this year has seen a huge number of improvements to scroll views, fun new SF Symbols effects, advanced support for Metal shaders, and more.

Some of these are things I’ve asked for personally, including the ability to add Metal shaders, making Color work better with Codable, adding a completion closure for animations, allowing us to animate gradients, and being able to selectively round corners of a rectangle – I’ve closed at least a dozen feedbacks just from beta 1!

Scroll view improvements

Drawing and animation improvements

More welcome improvements

And there’s more…

You might expect me to talk about SwiftData here, but I’m not – or at least not yet. Yes, it’s important, and yes it’s genuinely a huge step forward for all iOS developers, but I’m spending a lot of time writing test projects, experimenting, and getting answers to my questions, because I want to be really sure I understand it thoroughly before I write about it.

However, there are other interesting SwiftUI changes to discuss:

There’s improved API for filling and stroking shapes at the same time.
The onChange() modifier now accepts 0 or 2 parameters, and can also be triggered by your initial value
The foregroundColor() modifier has been formally deprecated in favor of foregroundStyle().
Changing colors in a gradient will animate in iOS 17 and later.
SwiftUI’s default animation is now a spring, there are many more built-in animations such as .bouncy and .snappy, and springs are now created with much simpler API.
There’s new support for rounding some corners of a rectangle but not others.
There’s newer, simpler syntax for making fill shapes and clip shapes: .rect, .capsule, and so on.
When creating table views, we can now write ForEach(users) rather than ForEach(users, content: TableRow.init)

And although it’s more of an Xcode improvement than a SwiftUI improvement, all images and colors defined in assets catalogs now have static names we can use in code rather than strings: Image(.dog) rather than Image("dog"), for example.

There are also new APIs for performing keyframe animations, new map controls, and more – I’m still digging in, writing code samples, and finding techniques that work well.

I particularly like some of the approaches taken in these new APIs, particularly the way things like scroll bar flashing, sensory feedback, and phase animations can be triggered using a simple Equatable comparison – it really lowers the complexity bar

So what about SwiftData?

The dramatic and wide-ranging changes to data management in SwiftUI are really welcome. In fact, there’s a video of me actually letting out a scream during Apple’s State of the Union session at Apple Park – I’m really glad to see it arrive.

However, it’s also something that takes care to get right. I’ll be updating my books for it – of course! – but I also want to make sure I understand the best practices for using it thoughtfully, so I hope you don’t mind a little delay while I’m conducting all my research.

Thank you for your patience!