How to Fix TextField Currency Formatting Issues in SwiftUI While Using Observed Objects

Learn how to resolve currency formatting issues in SwiftUI's `TextField` when using an `ObservedObject`. This guide provides a step-by-step solution to maintain focus and correct formatting.
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This video is based on the question https://stackoverflow.com/q/77484398/ asked by the user 'Eric Agredo' ( https://stackoverflow.com/u/5831955/ ) and on the answer https://stackoverflow.com/a/77484621/ provided by the user 'eric_b_231' ( https://stackoverflow.com/u/20566737/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Issue with TextField Currency Formatting in SwiftUI

If you’re working on a SwiftUI application and using ObservedObject, you might have stumbled upon a frustrating problem. The TextField meant for currency input behaves unexpectedly during interactions, particularly when used within a ForEach loop. This can disrupt user experience, leading to confusion and errors while entering data.

In this guide, we will dissect the issue and provide a robust solution that makes your currency inputs reliable and user-friendly.

The Problem

When utilizing multiple TextField elements in a ForEach structure linked to an ObservedObject, users may encounter the following:

The value auto-adjusts incorrectly when characters are deleted. For instance, if you started with 21.0 and deleted a number, it could round to $2.00.

The focus of the text field is lost after making an edit, which can be frustrating when trying to modify the input.

To illustrate this, consider the following example where we have a view model holding an array of TestItem elements populated with name and value:

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

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

As you make edits to the TextField linked to these TestItem objects, the peculiar behavior comes into play.

The Solution

To resolve these issues effectively, you need to ensure that each TestItem is uniquely identifiable. The following steps outline the enhancements needed:

Step 1: Make Your Model Identifiable

First, we will modify the TestItem struct to conform to the Identifiable protocol, which gives each instance a distinct identity. This helps maintain the focus on the TextField during user input.

Here’s how to adjust the struct:

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

Step 2: Update Your ForEach Loop

Now that the TestItem is identifiable, we can modify the ForEach loop to eliminate the focus loss issue:

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

Why Does This Work?

When using ForEach with .\self, SwiftUI struggles to identify and track the state of your views, causing them to lose focus when changes are applied. By ensuring that each TestItem has a unique id, SwiftUI can maintain correct states and focus during edits.

Conclusion

Implementing this solution provides a seamless user experience when interacting with TextField for currency inputs in your SwiftUI application. It preserves focus and delivers accurate behavior, giving your users the confidence they need as they input data.

By following these steps, you not only resolve the current dilemma but also enhance the overall robustness of your SwiftUI forms.

Happy coding!

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