Скачать или смотреть How to Scroll to a Relative Position in SwiftUI's ScrollView

Learn how to effectively scroll to a specific relative position within a horizontal ScrollView using SwiftUI.
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This video is based on the question https://stackoverflow.com/q/67488226/ asked by the user 'Isaak' ( https://stackoverflow.com/u/7399286/ ) and on the answer https://stackoverflow.com/a/67489453/ provided by the user 'jnpdx' ( https://stackoverflow.com/u/560942/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Scroll to a Relative Position in SwiftUI's ScrollView

If you're working with SwiftUI and have a long horizontal view that extends beyond the screen, you may encounter the challenge of navigating to a specific point within a ScrollView. In this post, we'll explore how to scroll to a relative position, such as 0.8, in a horizontal ScrollView. We'll break down the solution step by step, making it easy for you to implement this feature within your own applications.

The Problem

When you embed a large horizontal view within a ScrollView, you might find it challenging to scroll to a specific proportion of the view, especially when the contents do not have identifiable elements for the ScrollViewReader to anchor on. For instance, you may need to navigate directly to a position that represents 80% of the way to the right edge of your content view. Since traditional usage of ScrollViewReader relies on identifiable child elements, this can be a tricky task.

The Solution

Fortunately, there’s a straightforward way to achieve this using a combination of SwiftUI components. By utilizing a ZStack and invisible background views, you can create identifiable positions for scrolling purposes. Let’s walk through the code necessary to implement this solution.

Step 1: Set Up Your View

First, you need to create your ContentView struct, consisting of a horizontal ScrollView wrapped with a ScrollViewReader. Here’s how the setup looks:

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

Step 2: Understanding the Components

ScrollViewReader: This allows us to programmatically control the scroll position of the ScrollView. By wrapping it around our ScrollView, we gain access to the reader, which we can use for scrolling actions.

ZStack: This container allows us to overlay the text on top of the HStack where we place Spacer elements. The Spacers serve as invisible anchors and are each assigned an ID corresponding to their index.

ForEach: We create multiple Spacer views within the HStack loop to occupy space along the horizontal axis. Each Spacer is given a unique ID from 0 to 99, enabling the ScrollViewReader to reference these positions for scrolling.

Button: The button labeled "Go to 0.8" triggers the scroll action. When clicked, the reader.scrollTo(80) method scrolls the view to the position assigned to the ID 80, which corresponds to 80% (0.8) of your content length.

Step 3: Implementing the Scroll Function

When you run the above code and click the button, your horizontal ScrollView will smoothly scroll to the relative position of 0.8. This is made possible by the combination of the identifiers provided by Spacer elements and the powerful ScrollViewReader functionality.

Conclusion

Scrolling to a specific relative position within a horizontal ScrollView can seem daunting at first, but with the right approach and use of SwiftUI components, you can easily handle it. By utilizing ZStack, ScrollViewReader, and invisible identifiers, we successfully navigate hidden content in an elegant manner.

Now you can implement this in your SwiftUI apps to enhance user experience and provide smooth navigational options. Happy coding!