From 079e764f13588b413560a9e020f46fb007708b38 Mon Sep 17 00:00:00 2001
From: Maurice Parker <mo@vincode.io>
Date: Thu, 18 Nov 2021 17:09:42 -0600
Subject: [PATCH] Enable prefetching on iOS 15 to improve Timeline scrolling
 speed

---
 .../MasterTimelineViewController.swift        | 21 +++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/iOS/MasterTimeline/MasterTimelineViewController.swift b/iOS/MasterTimeline/MasterTimelineViewController.swift
index 83ec38ea6..808737c34 100644
--- a/iOS/MasterTimeline/MasterTimelineViewController.swift
+++ b/iOS/MasterTimeline/MasterTimelineViewController.swift
@@ -83,10 +83,6 @@ class MasterTimelineViewController: UITableViewController, UndoableCommandRunner
 		iconSize = AppDefaults.shared.timelineIconSize
 		resetEstimatedRowHeight()
 
-		if #available(iOS 15, *) {
-			tableView.isPrefetchingEnabled = false
-		}		
-		
 		if let titleView = Bundle.main.loadNibNamed("MasterTimelineTitleView", owner: self, options: nil)?[0] as? MasterTimelineTitleView {
 			navigationItem.titleView = titleView
 		}
@@ -579,8 +575,12 @@ class MasterTimelineViewController: UITableViewController, UndoableCommandRunner
 	}
 
 	@objc private func reloadAllVisibleCells() {
-		let visibleArticles = tableView.indexPathsForVisibleRows!.compactMap { return dataSource.itemIdentifier(for: $0) }
-		reloadCells(visibleArticles)
+		if #available(iOS 15, *) {
+			reconfigureCells(coordinator.articles)
+		} else {
+			let visibleArticles = tableView.indexPathsForVisibleRows!.compactMap { return dataSource.itemIdentifier(for: $0) }
+			reloadCells(visibleArticles)
+		}
 	}
 	
 	private func reloadCells(_ articles: [Article]) {
@@ -590,6 +590,15 @@ class MasterTimelineViewController: UITableViewController, UndoableCommandRunner
 			self?.restoreSelectionIfNecessary(adjustScroll: false)
 		}
 	}
+
+	private func reconfigureCells(_ articles: [Article]) {
+		guard #available(iOS 15, *) else { return }
+		var snapshot = dataSource.snapshot()
+		snapshot.reconfigureItems(articles)
+		dataSource.apply(snapshot, animatingDifferences: false) { [weak self] in
+			self?.restoreSelectionIfNecessary(adjustScroll: false)
+		}
+	}
 	
 	// MARK: Cell Configuring