How to Use ScrollViewReader.scrollTo Without Obscuring Section Headers in SwiftUI

Learn how to ensure that the `ScrollViewReader.scrollTo` method in SwiftUI correctly accounts for section header heights, keeping your target items fully visible.
---
This video is based on the question https://stackoverflow.com/q/78033138/ asked by the user 'Cesare' ( https://stackoverflow.com/u/14737138/ ) and on the answer https://stackoverflow.com/a/78033285/ provided by the user 'Sweeper' ( https://stackoverflow.com/u/5133585/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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 to Ensure ScrollViewReader.scrollTo Considers Section Header Height in SwiftUI?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Ensuring ScrollViewReader.scrollTo Considers Section Header Height in SwiftUI

When building applications with SwiftUI, it's common to use ScrollViewReader to allow users to programmatically scroll to specific items in a ScrollView. However, developers often encounter a frustrating issue where the targeted items end up partially obscured by a section header. This can compromise the user experience, especially when presenting data in a structured format.

In this post, we'll explore how to effectively address this problem by ensuring that the scroll position considers the height of section headers.

The Problem

Imagine developing a SwiftUI application that features a ScrollView with a LazyVStack that includes section headers. You might be tempted to use ScrollViewReader's scrollTo method to jump to a specific item.

However, the challenge arises when the item you scroll to ends up hidden under the section header:

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

In this snippet, when you tap the button designed to scroll to item 77, it may appear behind the section header, leaving the user unable to easily see the content.

The Solution

To fix this issue, you will need to consider three key components:

Height of the Section Header: This is the height you've set for the section header. In your case, it's 60 points.

Height of the Scroll View: You can determine this using a GeometryReader.

Height of the Item to Scroll To: The height of the views inside your LazyVStack, which is 50 points in your example.

Using these measurements, you can calculate a custom UnitPoint to use with the anchor: argument in the scrollTo call.

Step-by-Step Implementation

Here's how you can implement this solution:

Wrap the Scroll View in a GeometryReader

First, encapsulate your ScrollView within a GeometryReader to access the scroll view's dimensions.

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

Calculate the scrollViewHeight, sectionHeaderHeight, and contentHeight:

Here’s how to define these values:

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

Compute the UnitPoint:

Use the heights calculated above to create the required anchor for the scroll action. The formula looks like this:

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

Then, update your scrollTo call:

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

Handling Dynamic Heights

If your section header has a dynamic height instead of a fixed value, you can obtain this height through the same GeometryReader by utilizing:

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

Ensure you've named your coordinate space accordingly in your header view:

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

Conclusion

By following these steps, you can effectively use ScrollViewReader.scrollTo in SwiftUI without fear of obscuring content beneath section headers. This solution ensures that your UI remains intuitive and user-friendly, enhancing how your app presents its information.

Feel free to reach out if you have more questions or share your experiences with SwiftUI's scrolling mechanism!