How to Fix the UIImage Display Issue in SwiftUI Using EnvironmentObject

Learn how to display a `UIImage` stored in an EnvironmentObject in SwiftUI. Understand ObservableObject and why your image might not show up in your app.
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How to Fix the UIImage Display Issue in SwiftUI Using EnvironmentObject

In the world of SwiftUI, displaying images properly can sometimes lead to confusion, especially when working with UIImage and the EnvironmentObject concept. If you've found yourself in a situation where your images do not appear as expected in your SwiftUI view, you're not alone. Let's explore the problem and uncover a well-defined solution to get your images shown correctly.

The Problem

You have a struct that holds a UIImage stored in an EnvironmentObject, and you want to render this image in your SwiftUI view. However, despite your best efforts, the image simply does not display. You can confirm that the UIImage is correctly loaded from Firebase storage into your model data. Here’s a simplified overview of your struct and model:

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And your SwiftUI view is structured like this:

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Despite loading the images correctly and having the name property display as intended, the image doesn't show up in the view.

Understanding the Solution

Key Concept: ObservableObject and @ Published

To resolve this issue, we need to understand how ObservableObject and @ Published work within SwiftUI. The key detail here is that the UIImage must be observed for changes. If a property contained within an ObservableObject changes, SwiftUI needs to be notified to refresh the view.

Initially, your TestStruct was defined as a simple struct, meaning that SwiftUI doesn't listen for changes in its properties automatically. To fix this, TestStruct should be converted into a class and the image property made @ Published.

Revised Code: Updating TestStruct

Changing TestStruct to a class with the @ Published property looks like this:

[[See Video to Reveal this Text or Code Snippet]]

By making these changes, SwiftUI will now listen for updates to the image property within TestStruct, and it will trigger a view update whenever the image changes.

Final Steps: Conforming to ObservableObject

After you’ve updated the TestStruct, ensure that instantiating testStruct in the ModelData class allows for each instance to be observed properly. Update your modelData immediately after fetching data from Firebase.

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By converting your TestStruct to a class with an @ Published image property, you've enabled SwiftUI to react whenever the image updates. Remember that understanding ObservableObject and the use of @ Published plays a vital role in ensuring your UI reflects changes in your data model.

You should now see the image displayed in your SwiftUI view without any issues! Don't hesitate to explore and experiment more with SwiftUI's powerful data flow mechanisms, as it becomes second nature to create dynamic and reactive UIs.