Issue keeping scroll position in SwiftUI

Question

loics76 OP

Created 13h

Replies 1

Boosts 0

Participants 2

Hey there,

Link to the sample project: https://github.com/dev-loic/AppleSampleScrolling

Context

We are working on creating a feed of posts in SwiftUI. So far, we have successfully implemented a classic feed that opens from the top, with bottom pagination — a standard use case.

Our goal, however, is to allow the feed to open from any post, not just the first one.

For example, we would like to open the feed directly at the 3rd post and then trigger a network call to load elements both above and below it.

Our main focus here is on preserving the scroll position while opening the screen and waiting for the network call to complete.

To illustrate the issue, I created a sample project (attached) with two screens:

MainView, which contains buttons to open the feed in different states.
ScrollingView, which initially shows a single element, simulates a 3-second network call, and then populates with new data depending on which button was tapped.

I am currently using Xcode 26 beta 6, but I can also reproduce this issue on Xcode 16.3.

Tests on sample project

I click on a button and just wait the 3 seconds for the call.

In this scenario, I expect that the “focused item” stays at the exact same place on the screen. I also expect to see items below and above being added.

Simulator iPhone 16 / iOS 18.4 with itemsHeight = 100

position = 0, 1, 2, 3 ⇒ works as expected

position = 4, 5, 6, 7, 8, 9 ⇒ scroll is reset to the top and we loose the focused item

Simulator iPhone 16 / iOS 18.4 with itemsHeight = 500

position = 0, 1, 2, 3, 4 ⇒ works as expected

position = 5, 6, 7 ⇒ I have a glitch (the focused element moves on the screen) but the focused element is still visible

position = 8, 9 ⇒ scroll is reset to the top and we loose the focused item

Simulator iPhone 16 / iOS 26 with itemsHeight = 100 or 500

position = 0, 1, 2, 3, 4 ⇒ works as expected

position = 5, 6, 7, 8, 9 ⇒ I have a glitch (the focused element moves on the screen) but the focused element is still visible

Device iPhone 15 / iOS 26 with itemsHeight = 100

position = 0, 1, 2, 3, 4 ⇒ works as expected

position = 5, 6, 7, 8, 9 ⇒ I have a glitch (the focused element moves on the screen) but the focused element is still visible

Device iPhone 15 / iOS 26 with itemsHeight = 500

position = 0, 1, 2, 3 ⇒ works as expected

position = 4, 5, 6, 7, 8, 9 ⇒ I have a glitch (the focused element moves on the screen) but the focused element is still visible

Not any user interaction

Moreover, in this scenario, the user does not interact with the screen during the simulated network call. Regardless of the situation, if the ScrollView is in motion, its position always resets to the top. This behavior prevents us from implementing automatic pagination when scrolling upward, which is ultimately our goal.

My conclusion so far

As far as I know it seems not possible to have both keeping scroll possible and upward automatic pagination using a SwiftUI LazyVStack inside a ScrollView.

This appears to be standard behavior in messaging apps or other feed-based apps, and I’m wondering if I might be missing something.

Thank you in advance for any guidance you can provide on this topic.

Cheers

Boost

Answer 1

Vision Pro Engineer OP

Apple

4h

Hi @loics76 ,

You should look into ScrollViewReader and use proxy.scrollTo with the anchorID like:

ScrollViewReader { proxy in
  ScrollView {
     // .. content 
  }
  .onChange(of: viewModel.rows, { oldValue, newValue in
                withAnimation {
                    proxy.scrollTo(viewModel.anchorID)
                }
            })
}

What I've done here is check when the rows change (so more are loaded in) and then animate a scroll to the selected anchor ID that matches the id of the row you have selected.

You should have no need for the bindings for the current scroll position with this, but could be useful to keep depending on your full app.

let me know if this helps!

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