Solving the Computed Property Challenge in SwiftUI Reusable Views

Описание: Learn how to effectively handle computed properties in reusable `SwiftUI` views by using `@State` and `@Binding`. Here’s a step-by-step guide to resolving your issues with view updates!
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Solving the Computed Property Challenge in SwiftUI Reusable Views

If you're developing with the SwiftUI framework and have been experimenting with reusable views, you may encounter some perplexing issues, particularly when it comes to computed properties and state management. In this guide, we’ll dive into a common scenario where the computed property fails to update correctly due to how state is managed across reusable views. Let’s break this down and find a resolution to the problem simply and effectively.

The Problem: Computed Property not Updating

Imagine you’ve created a custom RatingView that allows users to rate different criteria (like a movie, game, etc.). You place this view within a parent view called ScoringView. However, as you try to adjust ratings through buttons in RatingView, you notice that the computed property, roundScore, in ScoringView remains at zero. Here’s the crux of the issue:

The properties used for tracking ratings in ScoringView are defined as simple integers.

When a user interacts with the buttons in RatingView, those changes don't trigger an update in the parent view because ScoringView doesn't recognize that it should refresh.

The Solution: Leveraging @State and @Binding

To address this problem, you need to implement state management correctly. By utilizing @State and @Binding properties, you can create a two-way connection between your ScoringView and RatingView that allows SwiftUI to update properly.

Step 1: Use @State in the Parent View

The first adjustment is to define the rating properties in ScoringView using @State. This way, SwiftUI understands that these values are subject to change and needs to trigger UI updates. Update your rating variables as follows:

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Step 2: Pass Ratings as @Binding to the Child View

Next, adjust your RatingView. Instead of having a let variable for the rating, which makes it immutable within the context of your view, switch to using a Binding. This allows any changes made in the RatingView to reflect back to ScoringView.

Here’s how to change the RatingView:

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Step 3: Use $ to Bind State Variables

While initializing the RatingView instances in your ScoringView, you need to use the $ prefix to denote that you're passing a binding. Modify the calls to RatingView like this:

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Final Code Sample

Here's how the updated ScoringView would look with these changes:

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Conclusion

By making these simple adjustments using @State and @Binding, your ScoringView will now reflect the changes made in RatingView properly. As you continue to develop with SwiftUI, remember that effective state management is crucial for the interactivity of your views. Happy coding!