Скачать или смотреть Solving the Picker Issue in SwiftUI: How to Store Selected Values

Discover how to resolve the issue of storing selected `Picker` values in SwiftUI. This guide provides effective solutions and tips for working with State and Binding in your SwiftUI applications.
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This video is based on the question https://stackoverflow.com/q/70637048/ asked by the user 'winston' ( https://stackoverflow.com/u/2089684/ ) and on the answer https://stackoverflow.com/a/70637957/ provided by the user 'workingdog support Ukraine' ( https://stackoverflow.com/u/11969817/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction: The Problem with Picker Values in SwiftUI

If you're developing a SwiftUI application and using a Picker to select values from a list, you might encounter a frustrating issue: the selected value not being stored correctly in your binding variable. In this guide, we will dissect a common scenario where the selected value returns as an empty string, even when the Picker is populated with a list of objects.

The issue can be particularly troublesome, especially when you have only one item in the array, as it can lead to confusion if the selection isn't registered by the UI. Let’s dive into the details of this problem and provide you with a clear solution.

Understanding the Problem

In the example provided, the GarageSpace view contains a Picker that allows users to select a car from the cars array. Here’s a snippet of the relevant code:

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Key Issues Identified

Initialized Value for selectedCar: The variable $selectedCar is not binding to an initialized value when GarageSpace is presented through NavigationLink, leading to an empty string.

Single Item Selection: If there's only one item in the Picker, it may not automatically select an item, leading to the appearance that nothing is being selected.

The Solution: Ensuring Picker Values Are Stored Correctly

Below, we outline a comprehensive approach to address these issues and ensure the Picker functions as expected.

Step 1: Initialize selectedCar Properly

To fix the initialization issue, ensure that we provide a default value for selectedCar within the GarageSpace view. For example:

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Step 2: Use Tags for Each Item in Picker

Using tags helps SwiftUI keep track of what is selected. Make sure to add tags for each item, allowing SwiftUI to properly register selections. Here’s how to do it:

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Step 3: Default Selection for Single Item Cases

When only one item is present, it’s useful to set the selection programmatically. This can be accomplished by adding an onAppear modifier that updates selectedCar whenever the view appears:

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Complete Example Code

Here’s how the complete GarageSpace view should look:

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Conclusion

By following the steps outlined above, you can initially set up a Picker in SwiftUI to work seamlessly with selections, ensuring that the selected value is appropriately stored in your binding variable.

If you follow these practices in your SwiftUI applications, you should find that handling selections, even with single items, becomes much more intuitive and user-friendly. Happy coding!