Issue 651

8^th March 2024

Written by Dave Verwer

Comment

Note: Please read the update at the end of this comment!

Swift 5.10 is here! Holly Borla introduced the release on the Swift.org blog, and if you haven’t dug into what this release is all about yet, I’ll let Holly explain by quoting the bolded sentence in her post:

Swift 5.10 accomplishes full data isolation in the concurrency language model.

As she explains, this is the culmination of years of work that will make our apps safer. In Swift 5.10, the feature to strictly check concurrency code is off by default and if switched on, introduces warnings, not errors.

The Swift Package Index isn’t the largest Swift project by a very long way, but it’s also not trivial, and it uses Swift concurrency extensively as a Vapor-based project, so I thought there would be no better way to test this than by enabling it on our codebase, so I did!

I followed this guide linked from Holly’s blog post and had it set up in a couple of minutes. I expected tens or maybe hundreds of warnings, but found zero! So I did a clean build and again found zero warnings. Deeply suspicious! 🕵️‍♂️

I chatted about it with Sven, and he suspects that we’re in such good shape because of the work he did with the Thread Sanitizer from some concurrency issues we had last year. The Thread Sanitizer does a similar job to these strict concurrency checks but at runtime. We still run our tests with the sanitiser switched on today.

Just to check I hadn’t messed up while enabling the feature, I quickly inserted some code I knew should trigger a warning, and sure enough, one appeared! It seems the Swift Package Index source code is ready for Swift 6! 🎉

Since switching it on didn’t add any warnings, I even committed those changes so we won’t accidentally introduce this class of error before Swift 6 arrives.

Checking for compatibility isn’t the only reason you would enable this flag, so why not give it a try to see how your apps fare? It only takes a minute to enable.

Update: I made a mistake here and used enableUpcomingFeature instead of enableExperimentalFeature. The real count of warnings was 526! 😱 Be careful how you enable it!

Dave Verwer

Code

Everything you need to know about Swift 5.10

Donny Wals goes into more detail about 5.10’s strict concurrency checks and includes a video on the subject for those of you who prefer to learn that way. 👍

Concurrency Recipes

I love this idea. Matt Massicotte has created a repository full of problems you may encounter while dealing with strict concurrency and solutions to help you get your code up to speed. The project is open for contributions, too, so if you find any problems you can’t solve, I’m sure even just contributing a description of the problem would be useful!

If you’ve created a visionOS app with a volume, you probably did it wrong

That’s a bold post title, but regardless of whether you got it wrong or not, there’s some useful information in this post from Drew Olbrich. He also followed up with more information on Volumes in a second post if you enjoy this one!

How to use TipKit to create tool tips in SwiftUI

I mentioned how much I liked that TipKit exists a couple of weeks ago, and along comes Natascha Fadeeva with a great article on getting started with them.

Design

Sometimes, a Button Just Wants to Look Like a Button

Max Rudberg:

What UI in your app could be solved better using a real world metaphor, or with just a really nice button?

I love all three examples in this post, but I especially like the button with the subtle blur behind it. ❤️

You can put your app’s paywall in an Alert. But you probably shouldn’t

I’d love to see more data on what Ryan Klumph is trying here. I can see an argument that the more in-depth and “heavy“ your paywall screen is, the more significant that decision might seem to people using your app. As Ryan says in the post, I agree it depends on the type of app and the IAP purchase price. Interesting idea, though!

Books

Creating iOSExpert

It’s likely that at some point in your career in this industry, you’ll either decide for yourself or be approached by a publisher to write a book or create a training course. Should you do it? I really enjoyed this post from Josh Adams about what he learned while producing his new course on preparing for a Swift/iOS interview.

Jobs

iOS Engineer @ trivago – trivago, a metasearch engine using real-time auction and petabytes of data, enables millions of travelers compare hotel prices from hundreds of booking sites. Based in Düsseldorf, we foster a culture of learning and innovation, embracing flexibility for our talents to shape the travel industry. – On-site (Germany) with some remote work (Anywhere)

Senior iOS/macOS Developer @ Paste – Joining Paste means crafting impactful, user-focused products alongside a team that values innovation, flexibility, and a culture of collaboration. Dive into projects that push the boundaries, enjoy freedom in how you work, and help shape the future of productivity tools. – Remote (within European timezones)

If you’d like to see your job featured in iOS Dev Weekly, post it on iOS Dev Jobs and select “Featured listing” as you check out, and it’ll be in next week’s newsletter. 🎉

And finally...

This looks like fun, especially if you have kids.

Also, don’t forget you can already run Swift on a Raspberry Pi Pico! 🫨