Changing the Color of a Button Inside a ForEach Loop in SwiftUI: An Easy Guide

Learn how to change the color of specific buttons in your SwiftUI app by using -State. This guide explains how to tackle the issue of updating values in a ForEach loop with clear and simple steps.
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This video is based on the question https://stackoverflow.com/q/69415707/ asked by the user 'alexisar' ( https://stackoverflow.com/u/17057136/ ) and on the answer https://stackoverflow.com/a/69416064/ 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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Changing the Color of a Button Inside a ForEach Loop in SwiftUI: An Easy Guide

If you are getting started with SwiftUI, you might encounter a common challenge when creating interactive user interfaces involving lists and buttons. Specifically, you might want to change the color of a button dynamically when it is pressed. In this guide, we'll explore how to achieve that while addressing a specific issue: modifying properties of a struct instance referenced in a ForEach loop.

The Problem: Changing Button Color

You have a list of buttons generated from a collection of workout routines, each with a name and an isActive state. When one of these buttons is pressed, you want to toggle the isActive state to change its color. Here’s a snippet of your code that describes the problem:

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The error arises because workout is declared as a constant (let), and you cannot modify its properties directly within the ForEach loop. Let’s dive into how to resolve this issue effectively.

The Solution: Using -State

To change the color of specific buttons, you need to make use of SwiftUI’s -State property wrapper. This approach allows you to maintain a mutable state across your view, enabling the buttons to update their properties when pressed.

Step-by-step Implementation

Define the Workouts with -State: Instead of declaring your workouts array as a constant, declare it as a -State variable. This change lets SwiftUI track changes to this array.

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Modify the ForEach Loop: Change the ForEach loop to use bindings, allowing you to directly modify the workout’s properties:

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Full Implementation Example

Here’s the complete updated code for the Workout_builder view:

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Conclusion

By utilizing -State, you can easily manage the state of your workout buttons and ensure that their colors reflect their active status. This technique is essential for creating interactive SwiftUI applications, and as you grow more familiar with these concepts, you'll feel more comfortable building complex UIs.

Now, take this knowledge and start experimenting with your SwiftUI projects! Changing button colors is just the beginning of what you can achieve with dynamic interfaces. Happy coding!

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