Fix CollectionView not scrolling to top on iOS status bar tap

[jfversluis]

Description

Fixes #19866

On iOS, tapping the status bar should scroll the topmost UIScrollView to the top. This was not working for CollectionView, particularly when hosted inside a Shell.

Root Cause

iOS disables its scroll-to-top behavior when multiple UIScrollView instances in the view hierarchy have scrollsToTop = true. The Shell flyout's internal AccessibilityNeutralTableView (a UITableView subclass) defaults scrollsToTop to true, conflicting with the CollectionView's UICollectionView.

Fix

Two changes:

1. ItemsViewController2.ViewDidLoad() — Explicitly set CollectionView.ScrollsToTop = true to opt in to scroll-to-top behavior
2. ShellTableViewController.AccessibilityNeutralTableView — Set ScrollsToTop = false on Shell's flyout table view to prevent the multi-scroll-view conflict

This follows the existing codebase pattern where ScrollsToTop is explicitly managed (e.g., ShellSectionRootHeader and ContextActionCell both set it to false).

Validation

Verified with a Sandbox app using a grouped CollectionView inside a Shell with TabBar:

• Without fix: Diagnostic dump shows two scroll views with scrollsToTop=True → status bar tap does nothing
• With fix: Only MauiCollectionView has scrollsToTop=True → status bar tap scrolls to top correctly

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 34687

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 34687"

[jfversluis]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[MauiBot]

🚦 Gate — Test Verification

📊 Expand Full Gate — 5639e24 · Fix CollectionView not scrolling to top on iOS status bar tap

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Gate Result: ❌ FAILED

Platform: ios

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[MauiBot]

🤖 AI Summary

📊 Expand Full Review — 5639e24 · Fix CollectionView not scrolling to top on iOS status bar tap

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🔍 Pre-Flight — Context & Validation

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Issue: #19866 - [iOS] UICollectionView ScrollToTop does not work
PR: #34687 - Fix CollectionView not scrolling to top on iOS status bar tap
Platforms Affected: iOS (macCatalyst may also benefit)
Files Changed: 2 implementation, 0 test

Key Findings

• iOS disables scroll-to-top-on-status-bar-tap when multiple UIScrollView instances in the same window have scrollsToTop = true simultaneously
• Shell flyout's AccessibilityNeutralTableView (a UITableView subclass) defaults scrollsToTop to true, conflicting with CollectionView's UICollectionView
• PR's fix is in Items2/iOS/ — the current, non-deprecated handler path for iOS/MacCatalyst (not deprecated Items/)
• Established codebase pattern already exists: ShellSectionRootHeader and ContextActionCell both set ScrollsToTop = false for the same reason
• PR has NO test files — Gate ❌ FAILED because no tests were provided to verify the fix
• Issue reporter tried workaround via CollectionViewHandler.Mapper.AppendToMapping(...) but used deprecated Items/ handler path, not Items2/
• Diff is minimal: 3 lines added across 2 files (ItemsViewController2.cs + ShellTableViewController.cs)
• Prior agent review completed (same Gate failure, 5 try-fix attempts all passed regression tests)
• CollectionView.ScrollsToTop = true in ItemsViewController2.ViewDidLoad() is technically redundant (UICollectionView defaults to true) but makes intent explicit

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #34687	Set CollectionView.ScrollsToTop = true in ItemsViewController2.ViewDidLoad() + Set ScrollsToTop = false in AccessibilityNeutralTableView() constructor	❌ Gate FAILED (no tests)	ItemsViewController2.cs, ShellTableViewController.cs	3 lines total; class-level fix; follows codebase pattern

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[kubaflo]

FIx looks good, but maybe some tests are possible ;)