Fixing SwiftUI OnDelete Crashes using Indices and Bindings

Discover how to solve crashes in SwiftUI when using OnDelete with indices and bindings by following this guide. Improve your app's stability and performance!
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This video is based on the question https://stackoverflow.com/q/74522195/ asked by the user 'David Perez' ( https://stackoverflow.com/u/20559362/ ) and on the answer https://stackoverflow.com/a/74525205/ provided by the user 'Guillermo Jiménez' ( https://stackoverflow.com/u/14096169/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing SwiftUI OnDelete Crashes using Indices and Bindings

When building an iOS app with SwiftUI, you might encounter various challenges, one of which is managing the delete functionality within a list. If you're using a list to display study items and provide a way to delete them via a swipe action, you might face crashes when users edit text fields before deleting items. This article will explore the root cause of the issue and how to effectively resolve it.

The Problem

In many cases, SwiftUI developers rely on using indices within a ForEach loop to bind data to UI components. However, this approach can lead to unexpected behavior, especially when trying to delete an item while editing a text field. Specifically, in your application, you have created cards for each study item, allowing users to swipe left to delete items. The symptom was clear: typing in text fields would make the app crash when attempting to delete the item afterward.

Here’s a brief overview of the relevant code you were using:

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The usage of indices here creates a tight coupling between your UI and data model, leading to instability upon deletion while editing.

The Solution: Embrace Identifiable

To fix these issues, the solution lies in updating your data model to conform to the Identifiable protocol. This adjustment allows SwiftUI to manage data more effectively without relying on indices, making the code cleaner and less prone to crashes.

Step-by-Step Implementation

Update your Data Model:
Ensure your StudyItemModel conforms to Identifiable and incorporates a unique identifier for each item:

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

Modify the ForEach Loop:
Instead of iterating through indices, use the entire array directly with a binding. Here’s how you can modify your ForEach loop:

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

Complete Implementation Example:
Here’s how the entire view might look after these changes:

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

Benefits of This Approach

Reduced Crashes: By removing reliance on indices, you eliminate the potential for invalid state references.

Cleaner Code: Using identifiable items allows SwiftUI to manage the state more efficiently and enhances readability.

Improved User Experience: Your app will handle text editing and deletions more fluidly without interruptions or crashes.

Conclusion

By adopting a more robust data handling strategy with the Identifiable protocol in SwiftUI, you can significantly enhance the stability of your app when dealing with dynamic lists. Implementing these changes will ensure a smoother experience for users, particularly with operations like editing and deleting items in a list.

If you've faced similar issues or have solutions you'd like to share, feel free to leave a comment below!