Hi, my name is Donny

I'm a curious, passionate iOS Developer from The Netherlands who loves learning and sharing knowledge.

Take a look at my books

Practical Swift Concurrency

Learn everything you need to know to make optimal use of Swift Concurrency in your applications. This book covers everything from awaiting asynchronous method calls to building your own highly concurrent systems. It’s a great introduction for those looking to familiarize themselves with everything Swift Concurrency has to offer.

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Practical Combine

Practical Combine is a book aimed at intermediate to advanced developers who want to learn more about Apple's Combine framework. This book takes you all the way from the basics to building custom Combine publishers using Practical, useful examples that you can start using immediately.

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Practical Core Data

Practical Core Data is for intermediate to advanced developers who want to learn more about Core Data. Whether you're new to Core Data, or tried using it years ago, you'll find that Practical Core Data introduces you to all the essentials to get you up and running with the framework.

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Recent articles

Designing APIs with typed throws in Swift

February 22, 2024

When Swift 2.0 added the throws keyword to the language, folks were somewhat divided on its usefulness. Some people preferred designing their APIs with an (at the time) unofficial implementation of the Result type because that worked with both regular and callback based functions. However, the language feature got adopted and a new complaint came up regularly. The way throws in Swift was designed didn’t allow developers to specify the types of errors that a function could throw. In every...

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How to determine where tasks and async functions run in Swift?

February 16, 2024

Swift’s current concurrency model leverages tasks to encapsulate the asynchronous work that you’d like to perform. I wrote about the different kinds of tasks we have in Swift in the past. You can take a look at that post here. In this post, I’d like to explore the rules that Swift applies when it determines where your tasks and functions run. More specifically, I’d like to explore how we can determine whether a task or function will run on the...

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Comparing @Observable to ObservableObjects

February 6, 2024

With iOS 17, we’ve gained a new way to provide observable data to our SwiftUI views. Until iOS 17, we’d use either an ObservableObject with @StateObject, @ObservedObject, or @EnvironmentObject whenever we had a reference type that we wanted to observe in one of our SwiftUI views. For lots of apps this worked absolutely fine, but these objects have a dependency on the Combine framework (which in my opinion isn’t a big deal), and they made it really hard for developers...

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Writing code that makes mistakes harder

January 25, 2024

As we work on projects, we usually add more code than we remove. At least that’s how things are at the beginning of our project. While our project grows, the needs of the codebase change, and we start refactoring things. One thing that’s often quite hard to get exactly right when coding is the kinds of abstractions and design patterns we actually need. In this post, I would like to explore a mechanism that I like to leverage to make...

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Connecting your git repository with a remote server

January 18, 2024

Having a local git repository is a smart thing to do. It’s even smarter to push your local git repositories up to a remote server so that you can collaborate with others, clone your repository on a separate machine, or have a backup of your code in case you’re replacing your current development machine with another. A possibly less obvious benefit of hosting your git repository somewhere is that lots of git servers provide useful features like Pull Requests for...

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Understanding and resolving merge conflicts

January 10, 2024

Git is great, and when it works well it can be a breeze to work with. You push , pull, commit, branch, merge, but then… you get into a merge conflict, In this post, we’ll explore merge conflicts. We’ll look at why they happen, and what we can do to avoid running into merge conflicts in the first place. Let’s start by understanding why a merge conflict happens. Understanding why a merge conflict happens Git is usually pretty good at...

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