How to Programmatically Scroll in SwiftUI

Discover how to implement `programmatic scrolling` in SwiftUI, ensuring smooth user experiences without UI refresh.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How can I programmatically scroll in SwiftUI?

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Programmatically Scroll in SwiftUI: A Comprehensive Guide

SwiftUI provides a powerful way to create smooth and dynamic user interfaces, but when it comes to scrolling, many developers encounter challenges—especially when dealing with asynchronous data loading. In this post, we will tackle the question of how to programmatically scroll to a specific element in a SwiftUI ScrollView, particularly from a ViewModel without triggering a UI refresh.

The Problem

As applications grow in complexity, the need for programmatic scrolling becomes prominent. A common scenario is wanting to scroll to a specific element after all views have finished loading. When attempting to achieve this, many developers find it tricky to scroll to a specific index within a ScrollView using data from a ViewModel. This challenge is further complicated by the fact that we do not want to force a refresh of the entire view.

Key Requirements:

Scroll to a specific element once all data has loaded.

Ensure the scroll action occurs without a page refresh, akin to a button click.

The Solution

To solve this problem, we can leverage SwiftUI's ScrollViewReader in conjunction with an observable property in our ViewModel to track the index that we want to scroll to. Below, we provide a detailed breakdown of how to implement this solution effectively.

Step 1: Setup Your ViewModel

You need an ObservableObject ViewModel to hold the index of the view you want to scroll to. Here’s an example:

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

Step 2: Create the View with a ScrollViewReader

In your view, wrap your ScrollView with ScrollViewReader and use the onChange modifier to scroll when the selectedIndex changes:

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

Explanation of the Code:

ViewModel: The SomeViewModel class holds a selectedIndex that gets updated after simulating data loading.

ScrollView: We use a ScrollView wrapped with ScrollViewReader to enable programmatic scrolling.

onChange Modifier: The onChange modifier monitors changes to selectedIndex and triggers scrolling to the updated index whenever it changes.

Important Notes:

The method scrollTo(newIndex, anchor: .top) is called inside the onChange closure, ensuring the scroll only happens when the selectedIndex is updated.

This setup avoids the page refresh you wanted to prevent, mimicking the simplicity of a button click from the initial example.

Conclusion

By utilizing SwiftUI's ScrollViewReader along with an observable property in your ViewModel, you can efficiently manage programmatic scrolling without unwanted view refreshes. This approach not only makes your UI more responsive but also improves the overall user experience by delivering smooth and intentional navigation throughout your application.

Now, you can get back to building beautiful and functional interfaces with SwiftUI, knowing how to efficiently scroll programmatically! Happy coding!