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Testing completion handler APIs with Swift Testing

Published on: October 16, 2024

The Swift testing framework is an incredibly useful tool that allows us to write more expressive tests with convenient and modern APIs. This is my first post about Swift Testing, and I’m mainly writing it because I wanted to write about something that I encountered not too long ago when I tried to use Swift testing on a code base where I had both async code as well as older completion handler based code. The async code was very easy to test due to how Swift Testing is designed, and I will be writing more about that in the future....

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What is dependency injection in Swift?

Published on: October 11, 2024

Code has dependencies. It’s something that I consider universally true in one way or another. Sometimes these dependencies are third party dependencies while other times you’ll have objects that depend on other objects or functionality to function. Even when you write a function that should be called with a simple input like a number, that’s a dependency. We often don’t really consider the small things the be dependencies and this post will not focus on that at all. In an earlier post, I’ve written about using closures as dependencies, also known as protocol witnesses. In this post I’d like to...

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Getting started with Mesh Gradients on iOS 18

Published on: September 25, 2024

With iOS 18, we have the possibility to create mesh gradients. Mesh gradients are a really nice way to create very cool UI effects. In this post, we're going to explore exactly what mesh gradients are, how we can use them, and how we can even animate them to look really cool. We’ll start off looking at how we can create a mesh gradient. We're going to take a look at how it more or less works, and then we'll also look at what we can animate and how we can play with mesh gradients. At the end of the...

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Animating SF Symbols on iOS 18

Published on: September 4, 2024

Over the years, Apple has been putting tons of work into the SF Symbols catalog. With SF Symbols, we’re able to leverage built-in iconography that will look familiar to users while also fitting into the Apple ecosystem very nicely. The fact that there’s thousands of symbols to choose from makes it a highly flexible and powerful catalog of icons that, in my opinion, should be every designer and developer’s first choice when they’re looking for visual components to add to their apps. Initially, SF Symbols were pretty much static. We could configure them with a color and thickness but that...

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Solving “Value of non-Sendable type accessed after being transferred; later accesses could race;”

Published on: August 23, 2024

Once you start migrating to the Swift 6 language mode, you'll most likely turn on strict concurrency first. Once you've done this there will be several warings and errors that you'll encounter and these errors can be confusing at times. I'll start by saying that having a solid understanding of actors, sendable, and data races is a huge advantage when you want to adopt the Swift 6 language mode. Pretty much all of the warnings you'll get in strict concurrency mode will tell you about potential issues related to running code concurrently. For an in-depth understanding of actors, sendability and...

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Setting the Swift Language mode for an SPM Package

Published on: August 21, 2024

When you create a new Swift Package in Xcode 16, the Package.swift contents will look a bit like this: // swift-tools-version: 6.0 // The swift-tools-version declares the minimum version of Swift required to build this package. import PackageDescription let package = Package( name: "AppCore", products: [ // Products define the executables and libraries a package produces, making them visible to other packages. .library( name: "AppCore", targets: ["AppCore"]), ], targets: [ // Targets are the basic building blocks of a package, defining a module or a test suite. // Targets can depend on other targets in this package and products from...

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Solving “Task-isolated value of type ‘() async -> Void’ passed as a strongly transferred parameter”

Published on: August 21, 2024

Once you start migrating to the Swift 6 language mode, you'll most likely turn on strict concurrency first. Once you've done this there will be several warings and errors that you'll encounter and these errors can be confusing at times. I'll start by saying that having a solid understanding of actors, sendable, and data races is a huge advantage when you want to adopt the Swift 6 language mode. Pretty much all of the warnings you'll get in strict concurrency mode will tell you about potential issues related to running code concurrently. For an in-depth understanding of actors, sendability and...

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Solving “reference to var myVariable is not concurrency-safe because it involves shared mutable state” in Swift

Published on: August 15, 2024

Once you start migrating to the Swift 6 language mode, you'll most likely turn on strict concurrency first. Once you've done this there will be several warings and errors that you'll encounter and these errors can be confusing at times. I'll start by saying that having a solid understanding of actors, sendable, and data races is a huge advantage when you want to adopt the Swift 6 language mode. Pretty much all of the warnings you'll get in strict concurrency mode will tell you about potential issues related to running code concurrently. For an in-depth understanding of actors, sendability and...

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Solving “Converting non-sendable function value may introduce data races” in Swift

Published on: August 12, 2024

Once you start migrating to the Swift 6 language mode, you'll most likely turn on strict concurrency first. Once you've done this there will be several warings and errors that you'll encounter and these errors can be confusing at times. I'll start by saying that having a solid understanding of actors, sendable, and data races is a huge advantage when you want to adopt the Swift 6 language mode. Pretty much all of the warnings you'll get in strict concurrency mode will tell you about potential issues related to running code concurrently. For an in-depth understanding of actors, sendability and...

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What are Optionals in Swift?

Published on: August 12, 2024

In an earlier article, I explained how variables are defined in Swift using let and var. Both constants (let) and variables (var) in Swift always have a type; it's what makes Swift a strongly typed language. For example, we could define a String variable like this: // the compiler will know myString is a String var myString = "Hello, world" // we're explicitly telling the compiler that myString2 is a String var myString2: String = "Hello, world" This way of defining variables makes a lot of sense when it's possible to immediately assign a value to our variable. However, sometimes...

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