Swift’s Hidden Gem: Understanding the @retroactive Keyword

Introduction

As iOS developers, we often find ourselves working with system frameworks and third-party libraries. Sometimes, we need these types to conform to certain protocols, especially when working with SwiftUI. This is where Swift’s powerful but lesser-known @retroactive keyword comes into play. In this article, we'll dive deep into what this keyword does, why it's useful, and how to use it effectively in your iOS applications.

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The Challenge: Extending Types We Don’t Own

Imagine you’re building a SwiftUI app and need to present a UIImage in a sheet. The sheet modifier in SwiftUI requires its content to conform to the Identifiable protocol. But here's the catch: UIImage is a system type that we don't own, and it doesn't conform to Identifiable out of the box.

Traditionally, this would pose a challenge. We can’t modify the original UIImage class, and simply adding an extension might not be…