Hi, my name is Donny

Async/await will be the defacto way of doing asynchronous programming on iOS 15 and above. I've already written quite a bit about the new Swift Concurrency features, and there's still plenty to write about. In this post, I'm going to take a look at building an asynchronous image loader that has support for caching. SwiftUI on iOS 15 already has a component that allows us to load images from the network but it doesn't support caching (other than what’s already...

If you've worked with Combine at all in your applications you'll know what it means when I tell you that you should always retain your cancellables. Cancellables are an important part of working with Combine, similar to how disposables are an important part of working with RxSwift. For example, you might have built a publisher that wraps CLLocationManagerDelegate and exposes the user's current location with a currentLocation publisher that's a CurrentValueSubject<CLLocation, Never>. If you subscribe to this publisher it might...

One of my favorite concurrency problems to solve is building concurrency-proof token refresh flows. Refreshing authentication tokens is something that a lot of us deal with regularly, and doing it correctly can be a pretty challenging task. Especially when you want to make sure you only issue a single token refresh request even if multiple network calls encounter the need to refresh a token. Furthermore, you want to make sure that you automatically retry a request that failed due to...

Earlier, I published a post on Swift Concurrency's task groups. If you haven't read that post yet, and you're not familiar with task groups, I recommend that you read that post first because I won't be explaining task groups in this post. Instead, you will learn about a technique that you can use to work around a limitation of task groups. Task groups can run a number of child tasks where every child task in the task group produces the...

In last week's post, I demonstrated how you can use a task group in Swift to concurrently run multiple tasks that produce the same output. This is useful when you're loading a bunch of images, or in any other case where you have a potentially undefined number of tasks to run, as long as you (somehow) make sure that every task in your group produces the same output. Unfortunately, this isn't always a reasonable thing to do. For example, you...

With Apple's overhaul of how concurrency will work in Swift 5.5 and newer, we need to learn a lot of things from scratch. While we might have used DispatchQueue.async or other mechanisms to kick off multiple asynchronous tasks in the past, we shouldn't use these older concurrency tools in Swift's new concurrency model. Luckily, Swift Concurrency comes with many features already which means that for a lot of our old uses cases, a new paradigm exists. In this post, you...