Fixing SwiftUI's ForEach Not Updating Issue: From @ ObservedObject to @ StateObject

Discover how to solve the issue of SwiftUI's `ForEach` not updating with `@ Published` data by transitioning from `@ ObservedObject` to `@ StateObject`.
---
This video is based on the question https://stackoverflow.com/q/66263029/ asked by the user 'brettfazio' ( https://stackoverflow.com/u/3853879/ ) and on the answer https://stackoverflow.com/a/66752350/ provided by the user 'brettfazio' ( https://stackoverflow.com/u/3853879/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: SwiftUI identifiable ForEach doesn't update when initially starting with empty

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Solving the SwiftUI ForEach Not Updating Issue: Switching to @ StateObject

If you’re a SwiftUI developer, you may have encountered a frustrating scenario where your ForEach view does not update even after fetching new data from your backend. This can occur when working with state management and observable objects in SwiftUI, especially within complex views. In this guide, we’ll explore this problem in-depth and provide a straightforward solution that involves simply changing the property wrapper used with your model.

The Problem: ForEach Not Reflecting Changes

Recently, a developer faced an issue where their SwiftUI view, specifically a SummaryView, failed to update even after successfully fetching data. The model.accounts array was supposed to hold the fetched accounts and trigger the UI update via @ Published when updated. However, the data remained empty when first displayed.
Here’s a summary of the original code setup:

Parent View: Contains the SummaryView as part of its layout.

Summary View: Uses an ObservedObject to hold the data model. It attempts to display the accounts using ForEach but remains empty on initial load.

View Model: Fetches the accounts from an API and updates the @ Published variable.

Despite the data successfully being fetched and set in the AccountsSummaryViewModel, the UI did not reflect these changes upon the first appearance of the SummaryView. This led to confusion, particularly because switching to a different view and then coming back displayed the fetched accounts correctly.

The Solution: Moving from @ ObservedObject to @ StateObject

The key to solving the issue was understanding the difference between @ ObservedObject and @ StateObject. Here’s a clear breakdown of what these two property wrappers do:

Understanding @ ObservedObject

Usage: Used for observing an external ObservableObject.

Behavior: The data is not owned by the view; rather, the view reacts to changes from another source.

Limitation: This can lead to issues when the view is initialized, especially if the model is created elsewhere.

Understanding @ StateObject

Usage: Introduced in iOS 14, this property wrapper is definitive for managing an instance of ObservableObject within a view.

Behavior: The view owns this model, and it persists for the entire lifetime of the view.

Advantage: Ensures that the view correctly listens to changes in the model and updates its state accordingly.

Implementation: Changing the Code

To fix the issue in your code, simply change the @ ObservedObject syntax to @ StateObject in the SummaryView. Here’s how the modified code looks:

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

By switching to @ StateObject, the SummaryView properly maintains an instance of AccountsSummaryViewModel, ensuring that updates to accounts trigger a UI refresh as intended.

Conclusion

If you find yourself in a situation where your SwiftUI ForEach doesn't update as expected after fetching data, check if you are using @ StateObject instead of @ ObservedObject. This simple adjustment can help your views reflect real-time data changes correctly without the need for navigating away and back again. Keep practicing and refining your SwiftUI skills, and happy coding!

Видео Fixing SwiftUI's ForEach Not Updating Issue: From @ ObservedObject to @ StateObject канала vlogize