Скачать или смотреть How to Fix Picker in NavigationView Not Refreshing with SwiftUI

Learn how to ensure your `Picker` displays the correct value in a `NavigationView` when using custom bindings in SwiftUI. This solution simplifies your code using @ AppStorage.
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This video is based on the question https://stackoverflow.com/q/65106784/ asked by the user 'DJJazz' ( https://stackoverflow.com/u/2751978/ ) and on the answer https://stackoverflow.com/a/65108229/ provided by the user 'DJJazz' ( https://stackoverflow.com/u/2751978/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fix Picker in NavigationView Not Refreshing with SwiftUI

When working with SwiftUI, developers often encounter challenges related to state management. One specific issue that can arise is when a Picker inside a NavigationView does not refresh its displayed value after changing the selected option. This can lead to some confusion, particularly if you're trying to bind the Picker to an enum value that is stored in UserDefaults.

In this guide, we’ll tackle this problem and provide a clear solution that simplifies your code and makes use of SwiftUI's built-in features.

The Problem: Non-Refreshing Picker

You may have encountered a situation where you save an enum value to UserDefaults using a custom binding. While the saving functionality works correctly, the displayed value in the NavigationView does not update when the Picker selection changes.

Here’s a snippet of what you might be dealing with:

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

This code attempts to retrieve and set the weather condition but lacks the refresh functionality in SwiftUI, causing the UI to remain static even when the selection changes.

The Solution: Simplifying with @ AppStorage

Thanks to a helpful suggestion from community members, the ideal fix for this problem involves using @ AppStorage. This powerful property wrapper automatically observes changes to the value stored in UserDefaults and refreshes the UI accordingly.

Implementation Steps

Here’s how you can update your SwiftUI code to solve the issue:

Import SwiftUI: Make sure you're using the SwiftUI framework.

Define Your Enum: Keep the enum for your weather conditions as it is.

Use @ AppStorage: Replace the custom binding with the @ AppStorage property wrapper.

Here’s the complete revised code:

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

Benefits of Using @ AppStorage

Automatic Updates: When the picker selection changes, the UI will automatically refresh to show the new value.

Simpler Code: The implementation becomes cleaner as you no longer need to manually manage the binding.

User-Friendly: This enhances the user experience, allowing for seamless interaction with the UI.

Conclusion

Using @ AppStorage in SwiftUI simplifies managing state when working with UserDefaults, particularly in situations involving UI components like Picker inside a NavigationView. By adopting this approach, you can ensure that your app remains responsive and user-friendly.

Whether you are building weather apps or any other application utilizing enums and user preferences, integrating @ AppStorage will save you time and reduce complexity. Happy coding!