How to Detect the Bottom of a List in SwiftUI for Infinite Scrolling

Discover a step-by-step guide on how to implement infinite scrolling in SwiftUI by detecting the bottom of a list. Learn to load more data seamlessly without conventional arrays.
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Detecting the Bottom of a List in SwiftUI for Infinite Scrolling

In the world of app development, infinite scrolling has become a popular feature that enhances user experience by loading additional data seamlessly as the user scrolls. If you're using SwiftUI and struggle with detecting when the user reaches the bottom of a list, you're not alone. In this guide, we will explore how to tackle this common issue effectively.

The Problem

Imagine you have a dataset returned from an API that includes multiple items. You want your application to load more data automatically as the user scrolls to the bottom of the list, making navigation smooth and engaging. However, you might encounter challenges such as:

Loading only the initial data set or all data at once

Making sure to fetch new data when the last row of the list becomes visible

In SwiftUI, this can be achieved optimally by utilizing the onAppear modifier correctly. Let's dive into a practical solution starting with the data structure involved.

Data Structure

The dataset is encapsulated in the following structures, which include the response model and the individual result items:

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Example Data

For instance, you may receive a payload like this:

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The Solution

To effectively implement infinite loading, the onAppear modifier needs to be placed correctly within your list. Let's break down the solution step-by-step.

1. Define Your ViewModel

Your view model should conform to the ObservableObject protocol, managing the loading of data as follows:

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2. Setup the View

In your view, observe the Newsfeed class and use the ForEach loop to display the items. Ensure you correctly implement the loading of more data on row appearance:

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

3. Key Changes Explained

Position of onAppear: By placing onAppear inside the ForEach loop, you can detect when the currently rendered item is the last item in the array.

Conditional Check: You check if the current item is the last in the dataset before initiating an API call to load more data.

Increment Page: After the API call, increase the page number to keep track of which dataset to load next.

Conclusion

With this setup, your SwiftUI application will easily recognize when the user reaches the bottom of the list and will fetch more data automatically. By correctly placing the onAppear modifier and managing your state, infinite scrolling can significantly enhance the user experience in your application.

If you have any questions or face issues while implementing this feature, feel free to ask in the comments below! Happy coding!