Matteo Manferdini

Matteo has been developing apps for iOS since 2008. He has been teaching iOS development best practices to hundreds of students since 2015 and he is the developer of Vulcan, a macOS app to generate SwiftUI code. Before that he was a freelance iOS developer for small and big clients, including TomTom, Squla, Siilo, and Layar. Matteo got a master's degree in computer science and computational logic at the University of Turin. In his spare time he dances and teaches tango.

The Little-Known Root-View Technique for Improving MVVM in SwiftUI That Most Developers Overlook

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On the Internet, you can find plenty of SwiftUI tutorials that dive straight into building user interfaces without much consideration for underlying architectural principles.

While these examples can get you started, they often lead to a common pitfall: massive SwiftUI views, i.e., views that are hundreds or even thousands of lines long, brimming with disparate logic.

In this article, I will explain why massive views are a problem and introduce a robust approach to building modular SwiftUI views that are more reusable, easier to understand, and instantly previewable in Xcode.

MVVM in SwiftUI for a Better Architecture [with Example]

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Since the introduction of SwiftUI, the MVVM pattern has become more relevant than ever. Many developers believe this particular pattern aligns well with the SwiftUI data flow.

MVVM incorporates good ideas but also introduces problems due to varying interpretations of the pattern and its perceived rigidity.

In this article, we’ll explore how MVVM fits into SwiftUI, how to leverage its advantages, and how to navigate its challenges.

SwiftUI Data Flow: Passing Data Between Views

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SwiftUI offers several mechanisms to pass data between views.

If it seems complicated to decide which data flow mechanism fits your particular situation, that’s because such decisions cannot be made in isolation.

However, when you keep an app’s architecture in mind, it becomes easier to make the correct choice.

Downloading files from URLs in Swift [SwiftUI Architecture]

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Downloading files in Swift can be pretty straightforward, thanks to URLSession and URLSessionDownloadTask.

Moreover, tracking the progress of a download can be easily achieved with URLSessionDownloadDelegate.

However, SwiftUI apps often need to track the download progress of multiple files, complicating their networking architecture.

URLSession in Swift: The Essential Guide [with Examples]

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When you need to download or upload data in Swift, the URLSession class is the solution you should reach for.

URLSession handles the most common Internet protocols and allows you to:

  • Group and optimize data transfers.
  • Handle authentication, cookies, and caching.
  • Pause, resume, or cancel a download.
  • Download data in the background when your app is suspended.

AsyncStream and AsyncSequence for Swift Concurrency

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Asynchronous sequences are a core feature of Swift concurrency. They allow you to process asynchronous events easily using simple for loops.

However, conforming to the AsyncSequence protocol to create an asynchronous sequence is not straightforward.

That’s where AsyncStream comes to the rescue, allowing you to easily create asynchronous sequences and quickly adapt old APIs to Swift concurrency.

AsyncImage in SwiftUI: Loading Images from URLs [with Caching]

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AsyncImage is a convenient SwiftUI view that loads remote images using a URL. It’s especially useful in apps that interact with REST APIs since images are usually referenced using URLs in JSON data.

While Apple’s documentation might lead you to believe that AsyncImage caches the downloaded images, that is not the case. If you need image caching, you must implement your own custom solution.