Arek Holko

Hi! I'm Arek Holko. I build iOS apps for others and as an indie developer. I write mostly about iOS development. More about me.

Recent Articles

Hiding Implementation Details Using internal Properties

Swift comes with five access-level modifiers: open, public, internal, fileprivate and private. The internal modifier leads to entities being available for use only within their defining module. It’s a default modifier but it starts getting interesting only once we split our codebase into modules.

In this article, we’ll see how to provide an ability to inject a framework’s data structure into the framework’s classes, while at the same time keeping its internals hidden.

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Why #if DEBUG Conditional Should Be Avoided in Library Code

Conditional Compilation along with Active Compilation Conditions is a way to alter the app’s behavior depending on the build configuration. For example for the code to compile only in the Debug configuration, we can do:


In this article, I’ll show why these kinds of conditional blocks shouldn’t be used directly in the source code of libraries distributed to other developers.

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Future-Proof Dependency Injection for Storyboard-Based View Controllers

One of the issues introduced by storyboards is that they make it impossible to pass dependencies to view controllers in initializers. I proposed an API modification in past that would allow for exactly that, but alas, it doesn’t seem to be high on the priority list for UIKit. I recently came up with a new approach leveraging code generation which I’m excited to show you today.

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Stop Xcode from constantly rebuilding your project because of @IBDesignable

If you use Interface Builder along with @IBDesignable attribute you may have noticed that Xcode sometimes builds your project even though you didn’t trigger a build. This is because it needs to compile views marked with @IBDesignable to be able to render them in Interface Builder. What's problematic is that these builds seem to occur a bit too often.

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Optimizing Swift build times

I spent some time recently trying to optimize build times of a project I contribute to. To my surprise, the knowledge needed to do that was scattered around many blog posts and tweets. So, I decided to do something about that by putting everything I knew and learned in a single document. It's available on GitHub here.

Hope you learn something new!