Скачать или смотреть How to Animate a Bool Change in SwiftUI with Structs Effectively

Learn how to implement 3D animations in SwiftUI when a `Bool` changes in a struct. This guide provides step-by-step instructions and solutions to common pitfalls.
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This video is based on the question https://stackoverflow.com/q/71283845/ asked by the user 'yawnobleix' ( https://stackoverflow.com/u/1308355/ ) and on the answer https://stackoverflow.com/a/71285972/ provided by the user 'malhal' ( https://stackoverflow.com/u/259521/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering 3D Animations in SwiftUI: Making Boolean Changes Interactive

In the world of iOS development, creating engaging user interfaces is crucial. One way to achieve this is through animations in SwiftUI. Many developers encounter issues when attempting to animate changes tied to a struct property, such as a Bool. In this guide, we will explore the specific problem of animating a struct boolean change using a 3D effect in SwiftUI and provide a clear solution to help you implement it seamlessly.

The Problem: Animation Not Triggering

Consider the scenario where you have a struct called Line containing a boolean property named isDone that tracks whether a line of text is complete. As a new line is entered and isDone is set to true, you want a 3D rotation animation to occur. However, the rotation may appear but without any animation effect.

Code Structure

Here's a brief overview of the critical components involved:

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With this setup, ForEach is used to render each line, but the animation does not behave as expected.

The Solution: Refactoring for Animation

Transitioning to Identifiable

One of the main issues is related to how you build your ForEach view with value types. For ForEach to track changes in value types such as structs, it requires a unique identifier. Here's how to modify your Line struct to conform to Identifiable:

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With this change, you can now create the ForEach like this:

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Correcting the Object Lifecycle Management

Next, ensure you manage your view model's lifecycle correctly. Instead of using @ ObservedObject, which creates a new object with every state change, utilize @ StateObject for a model that should persist while the view is alive:

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This change makes sure that the ViewModel persists during the lifecycle of the MainView, which is essential for animations to function correctly.

Implementing the Animation

Finally, incorporate your 3D animation effect in the LineView based on the isDone status:

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

Summary

To achieve a dynamic and engaging user experience with SwiftUI by animating changes to a boolean in a struct, follow the steps outlined:

Refactor your struct to conform to Identifiable to allow ForEach to track changes properly.

Use @ StateObject to manage your view model’s lifecycle appropriately.

Ensure your animation triggers correctly by linking it directly to the relevant properties.

By making these adjustments, your animation of the isDone state transition will work effectively, providing users with a visually appealing interaction.

Now you are equipped to create interactive components with 3D animations in SwiftUI, making your applications feel more dynamic and engaging. Happy coding!