Resolving Core Data Object Update Issues in SwiftUI Views

Learn how to fix the issue of views not updating with changes made to `Core Data` objects in `SwiftUI` by using the correct property observers.
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Resolving Core Data Object Update Issues in SwiftUI Views

When working with Core Data in SwiftUI, one common problem that developers encounter is the failure of views to update properly based on changes to a Core Data object. If you find that the interface doesn't reflect changes made to the underlying data model, don't worry! This guide will help you address the issue efficiently by explaining the right approach to observe changes in your Core Data objects.

The Problem Explained

In your SwiftUI application, you have a Core Data object named Config, which includes three boolean properties: turnedOn, isSoft, and willAppear. You've implemented toggle switches for the user to interact with these properties. However, you've observed that when a user toggles one of these switches, the corresponding view does not reflect the changes immediately. This could be due to the way you're observing changes to your Core Data object.

Code Overview

Here's a brief look at how you've structured your Config and toggle switches:

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

You are using @ ObservedObject to create a binding to your Config object, which is correct.

Each CustomToggle is supposed to affect the properties based on user interactions, particularly making sure that toggling turnedOn updates willAppear accordingly, and vice versa.

The Solution

Use of objectWillChange

The majority of the issues stem from the current use of didSet to observe property changes. SwiftUI does not trigger didSet when a property of a bound object changes. Instead, you should utilize objectWillChange, which is provided by the @ ObservedObject property wrapper for handling updates to the object.

Here’s how to implement this:

Updating your Toggle Implementation:

You should modify the toggle's body to observe objectWillChange as follows:

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

Managing State Updates

Synchronization with UI Thread:

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

Conclusion

By integrating objectWillChange into your CustomToggle implementation, you should see the interactive behaviors of your toggle switches correctly reflected in the SwiftUI views. This change ensures that your UI responds dynamically to changes in your Core Data objects, enhancing the user experience.

Now you are equipped with the right approach to handle Core Data updates effectively in your SwiftUI application. Happy coding!