Cleanup + use ScrollPoxy

Packages/Timeline/Sources/Timeline/TimelineMediaPrefetcher.swift

@@ -1,43 +0,0 @@
-import Models
-import Nuke
-import Observation
-import SwiftUI
-import UIKit
-
-@Observable final class TimelineMediaPrefetcher: NSObject, UICollectionViewDataSourcePrefetching {
-  private let prefetcher = ImagePrefetcher()
-
-  weak var viewModel: TimelineViewModel?
-
-  func collectionView(_: UICollectionView, prefetchItemsAt indexPaths: [IndexPath]) {
-    let imageURLs = getImageURLs(for: indexPaths)
-    prefetcher.startPrefetching(with: imageURLs)
-  }
-
-  func collectionView(_: UICollectionView, cancelPrefetchingForItemsAt indexPaths: [IndexPath]) {
-    let imageURLs = getImageURLs(for: indexPaths)
-    prefetcher.stopPrefetching(with: imageURLs)
-  }
-
-  private func getImageURLs(for indexPaths: [IndexPath]) -> [URL] {
-    guard let viewModel, case let .display(statuses, _) = viewModel.statusesState else {
-      return []
-    }
-    return indexPaths.compactMap {
-      $0.row < statuses.endIndex ? statuses[$0.row] : nil
-    }.flatMap(getImages)
-  }
-}
-
-private func getImages(for status: Status) -> [URL] {
-  var urls = status.mediaAttachments.compactMap {
-    if $0.supportedType == .image {
-      return status.mediaAttachments.count > 1 ? $0.previewUrl ?? $0.url : $0.url
-    }
-    return nil
-  }
-  if let url = status.card?.image {
-    urls.append(url)
-  }
-  return urls
-}

Packages/Timeline/Sources/Timeline/View/TimelineView.swift

@@ -6,7 +6,6 @@ import Network
 import StatusKit
 import SwiftData
 import SwiftUI
-import SwiftUIIntrospect
 
 @MainActor
 public struct TimelineView: View {
@@ -20,11 +19,9 @@ public struct TimelineView: View {
   @Environment(RouterPath.self) private var routerPath
 
   @State private var viewModel = TimelineViewModel()
-  @State private var prefetcher = TimelineMediaPrefetcher()
   @State private var contentFilter = TimelineContentFilter.shared
 
   @State private var wasBackgrounded: Bool = false
-  @State private var collectionView: UICollectionView?
 
   @Binding var timeline: TimelineFilter
   @Binding var pinnedFilters: [TimelineFilter]
@@ -67,18 +64,6 @@ public struct TimelineView: View {
     .if(canFilterTimeline && !pinnedFilters.isEmpty) { view in
       view.toolbarBackground(.hidden, for: .navigationBar)
     }
-    .onChange(of: viewModel.scrollToIndex) { _, newValue in
-      if let collectionView,
-         let newValue,
-         let rows = collectionView.dataSource?.collectionView(collectionView, numberOfItemsInSection: 0),
-         rows > newValue
-      {
-        collectionView.scrollToItem(at: .init(row: newValue, section: 0),
-                                    at: .top,
-                                    animated: false)
-        viewModel.scrollToIndex = nil
-      }
-    }
     .toolbar {
       toolbarTitleView
       toolbarTagGroupButton
@@ -193,25 +178,23 @@ public struct TimelineView: View {
       .id(client.id)
       .environment(\.defaultMinListRowHeight, 1)
       .listStyle(.plain)
-      #if !os(visionOS)
-        .scrollContentBackground(.hidden)
-        .background(theme.primaryBackgroundColor)
-      #endif
-        .introspect(.list, on: .iOS(.v17, .v18)) { (collectionView: UICollectionView) in
-          DispatchQueue.main.async {
-            self.collectionView = collectionView
-          }
-          prefetcher.viewModel = viewModel
-          collectionView.isPrefetchingEnabled = true
-          collectionView.prefetchDataSource = prefetcher
+#if !os(visionOS)
+      .scrollContentBackground(.hidden)
+      .background(theme.primaryBackgroundColor)
+#endif
+      .onChange(of: viewModel.scrollToId) { _, newValue in
+        if let newValue {
+          proxy.scrollTo(newValue, anchor: .top)
+          viewModel.scrollToId = nil
         }
-        .onChange(of: selectedTabScrollToTop) { _, newValue in
-          if newValue == 0, routerPath.path.isEmpty {
-            withAnimation {
-              proxy.scrollTo(ScrollToView.Constants.scrollToTop, anchor: .top)
-            }
+      }
+      .onChange(of: selectedTabScrollToTop) { _, newValue in
+        if newValue == 0, routerPath.path.isEmpty {
+          withAnimation {
+            proxy.scrollTo(ScrollToView.Constants.scrollToTop, anchor: .top)
           }
         }
+      }
     }
   }
 

Packages/Timeline/Sources/Timeline/View/TimelineViewModel.swift

@@ -7,7 +7,7 @@ import SwiftUI
 
 @MainActor
 @Observable class TimelineViewModel {
-  var scrollToIndex: Int?
+  var scrollToId: String?
   var statusesState: StatusesState = .loading
   var timeline: TimelineFilter = .home {
     willSet {
@@ -229,13 +229,11 @@ extension TimelineViewModel: StatusesFetcher {
     {
       await datasource.set(cachedStatuses)
       let statuses = await datasource.getFiltered()
-      if let latestSeenId = await cache.getLatestSeenStatus(for: client, filter: timeline.id)?.first,
-         let index = await datasource.indexOf(statusId: latestSeenId),
-         index > 0
+      if let latestSeenId = await cache.getLatestSeenStatus(for: client, filter: timeline.id)?.first
       {
         // Restore cache and scroll to latest seen status.
+        scrollToId = latestSeenId
         statusesState = .display(statuses: statuses, nextPageState: .hasNextPage)
-        scrollToIndex = index + 1
       } else {
         // Restore cache and scroll to top.
         withAnimation {
@@ -299,6 +297,9 @@ extension TimelineViewModel: StatusesFetcher {
   }
   
   private func updateTimelineWithNewStatuses(_ newStatuses: [Status]) async {
+    defer {
+      canStreamEvents = true
+    }
     let topStatus = await datasource.getFiltered().first
     await datasource.insert(contentOf: newStatuses, at: 0)
     if let lastVisible = visibleStatuses.last {
@@ -313,30 +314,12 @@ extension TimelineViewModel: StatusesFetcher {
        visibleStatuses.contains(where: { $0.id == topStatus.id }),
        scrollToTopVisible
     {
-      updateTimelineWithScrollToTop(newStatuses: newStatuses, statuses: statuses, nextPageState: .hasNextPage)
+      scrollToId = topStatus.id
+      statusesState = .display(statuses: statuses, nextPageState: .hasNextPage)
     } else {
-      updateTimelineWithAnimation(statuses: statuses, nextPageState: .hasNextPage)
-    }
-  }
-
-  // Refresh the timeline while keeping the scroll position to the top status.
-  private func updateTimelineWithScrollToTop(newStatuses: [Status], statuses: [Status], nextPageState: StatusesState.PagingState) {
-    pendingStatusesObserver.disableUpdate = true
-    statusesState = .display(statuses: statuses, nextPageState: nextPageState)
-    scrollToIndex = newStatuses.count + 1
-
-    DispatchQueue.main.async { [weak self] in
-      self?.pendingStatusesObserver.disableUpdate = false
-      self?.canStreamEvents = true
-    }
-  }
-
-  // Refresh the timeline while keeping the user current position.
-  // It works because a side effect of withAnimation is that it keep scroll position IF the List is not scrolled to the top.
-  private func updateTimelineWithAnimation(statuses: [Status], nextPageState: StatusesState.PagingState) {
-    withAnimation {
-      statusesState = .display(statuses: statuses, nextPageState: nextPageState)
-      canStreamEvents = true
+      withAnimation {
+        statusesState = .display(statuses: statuses, nextPageState: .hasNextPage)
+      }
     }
   }