Fix for iOS CollectionView2 ItemSizingStrategy="MeasureFirstItem" Fails to Apply Correct Sizing by SuthiYuvaraj · Pull Request #29496 · dotnet/maui

SuthiYuvaraj · 2025-05-14T14:10:36Z

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Issue Description

When CollectionView2 uses ItemSizingStrategy, the sizing does not update correctly on iOS and macOS platforms.

RootCause

In CollectionView2 , ItemsLayout is directly derived from UICollectionViewController , where the ItemSizing is not considered.

Description of Change

In TemplatedCell2 , each cell is measured by a override method called PreferredLayoutAttributesFittingAttributes which will determine the size of each at initial loading , I have restricted the measure for all items when ItemSizingStatergy is MeasureFirstItem and updated the dynamic changes from GetCell in ItemsViewController2.

Issues Fixed

Fixes #29130
Fixes #23304

Tested the behaviour in the following platforms

Android
Windows
iOS
Mac

Output Screenshot

Before Issue Fix	After Issue Fix
ItemSizingBefore.mov	ItemSizeAfter.mov

jsuarezruiz · 2025-05-16T05:51:11Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-05-16T05:51:22Z

Azure Pipelines successfully started running 1 pipeline(s).

jsuarezruiz · 2025-05-16T10:52:00Z

src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs

+		}
+	}
+}
+public class CollectionViewViewModel


Modify this class to be something unique like Issue29130ViewModel.

/Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [/Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-maccatalyst] /Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [/Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-tizen] /Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [/Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-ios] /Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [/Users/builder/azdo/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-android] 1 Warning(s) 4 Error(s)

C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Issues\Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-windows10.0.20348.0] C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Issues\Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-windows10.0.19041.0] 2 Error(s)

Could you rename to Issue29130ViewMode?

jsuarezruiz · 2025-07-01T07:14:33Z

/rebase

jsuarezruiz · 2025-07-01T07:15:52Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-07-01T07:16:04Z

Azure Pipelines successfully started running 1 pipeline(s).

jsuarezruiz · 2025-07-01T07:34:00Z

src/Controls/tests/TestCases.HostApp/Issues/Issue29130.cs

+		}
+	}
+}
+public class CollectionViewViewModel


C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Issues\Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-windows10.0.20348.0] C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Issues\Issue29130.cs(88,14): error CS0101: The namespace 'Maui.Controls.Sample.Issues' already contains a definition for 'CollectionViewViewModel' [C:\a\_work\1\s\src\Controls\tests\TestCases.HostApp\Controls.TestCases.HostApp.csproj::TargetFramework=net9.0-windows10.0.19041.0] 2 Error(s)

Could you rename to Issue29130ViewMode?

SuthiYuvaraj · 2025-07-15T12:23:19Z

@jsuarezruiz, I have updated both the fix and the test case. Please review them and let me know if you have any feedback or concerns.

jsuarezruiz · 2025-09-08T07:13:07Z

/azp run

azure-pipelines · 2025-09-08T07:13:27Z

Azure Pipelines successfully started running 3 pipeline(s).

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…130.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

sheiksyedm · 2025-11-21T09:31:53Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-11-21T09:32:06Z

Azure Pipelines successfully started running 1 pipeline(s).

sheiksyedm · 2025-11-24T14:35:28Z

/azp run MAUI-UITests-public

azure-pipelines · 2025-11-24T14:35:39Z

Azure Pipelines successfully started running 1 pipeline(s).

SuthiYuvaraj · 2025-11-25T04:24:54Z

Can we move the firstItemMeasureSize reset call into "reloadData"?

I think all of the paths you have here will hit the reloadData call which will be a nice central place for this.

Hi @PureWeen , In ItemsViewController2, ReloadData is a native UICollectionView method, I’ve introduced an internal method called Reload(). The firstItemMeasureSize cache is being reset inside ReloadData, and since all relevant paths eventually invoke reloadData, the reset is handled centrally there. Please review this approach and let me know if you have any concerns.

…ls to Apply Correct Sizing (#29496) * Fix for ItemSizing issue * Update ItemsViewController2.cs * Update TemplatedCell2.cs * Update TemplatedCell2.cs * Update TemplatedCell2.cs * commit for itemsize * unwanted changes * commit for testcases * Update Issue29130.cs * ItemSizingStatergy changes * Update ItemsViewController2.cs * Update TemplatedCell2.cs * Changes for review * Update TemplatedCell2.cs * Update src/Controls/src/Core/Handlers/Items2/iOS/TemplatedCell2.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Update src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29130.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Update TemplatedCell2.cs * Update TemplatedCell2.cs * Update Issue29130.cs * commit for template testcases * Handler changes * Update ItemsViewHandler2.iOS.cs * Changes on ReloadData --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

dotnet-policy-service bot added community ✨ Community Contribution partner/syncfusion Issues / PR's with Syncfusion collaboration labels May 14, 2025

jsuarezruiz added the collectionview-cv2 label May 16, 2025

jsuarezruiz suggested changes May 16, 2025

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PureWeen added this to the .NET 9 SR9 milestone Jun 9, 2025

PureWeen added this to MAUI SDK Ongoing Jun 9, 2025

github-project-automation bot moved this to Todo in MAUI SDK Ongoing Jun 9, 2025

PureWeen moved this from Todo to In Progress in MAUI SDK Ongoing Jun 9, 2025

github-actions bot force-pushed the fix-29130 branch from 672832b to 1d65ca0 Compare July 1, 2025 07:15

jsuarezruiz suggested changes Jul 1, 2025

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github-project-automation bot moved this from In Progress to Changes Requested in MAUI SDK Ongoing Jul 1, 2025

PureWeen modified the milestones: .NET 9 SR9, .NET 9 SR10 Jul 3, 2025

SuthiYuvaraj marked this pull request as ready for review July 15, 2025 12:23

SuthiYuvaraj requested a review from a team as a code owner July 15, 2025 12:23

SuthiYuvaraj requested review from jfversluis and jsuarezruiz July 15, 2025 12:23

PureWeen modified the milestones: .NET 9 SR10, .NET 9 SR11 Aug 4, 2025

PureWeen added platform/ios area-controls-collectionview CollectionView, CarouselView, IndicatorView labels Aug 7, 2025

PureWeen removed this from the .NET 9 SR11 milestone Sep 10, 2025

SuthiYuvaraj and others added 8 commits November 20, 2025 20:15

Update src/Controls/src/Core/Handlers/Items2/iOS/TemplatedCell2.cs

d1acead

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29…

4cb0934

…130.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update TemplatedCell2.cs

d7fd5ca

Update TemplatedCell2.cs

54e0d63

Update Issue29130.cs

a40dc34

commit for template testcases

44cab91

Handler changes

2c1be39

Update ItemsViewHandler2.iOS.cs

d609c1e

github-actions bot force-pushed the fix-29130 branch from 49c3fd9 to d609c1e Compare November 20, 2025 20:15

Changes on ReloadData

dc3fdb0

SuthiYuvaraj force-pushed the fix-29130 branch from b8f2396 to dc3fdb0 Compare November 24, 2025 09:27

sheiksyedm moved this from Changes Requested to Ready To Review in MAUI SDK Ongoing Nov 25, 2025

StephaneDelcroix changed the base branch from main to inflight/current December 2, 2025 15:58

StephaneDelcroix approved these changes Dec 2, 2025

View reviewed changes

StephaneDelcroix merged commit 0a09df4 into dotnet:inflight/current Dec 2, 2025
128 of 163 checks passed

github-project-automation bot moved this from Ready To Review to Done in MAUI SDK Ongoing Dec 2, 2025

This was referenced Dec 15, 2025

[NET 10] I6_Grouping - Grouping_with_variable_sized_items changing the 'ItemSizingStrategy' also changes the header size. #33130

Closed

[iOS, macOS] Fixed CollectionView group header size changes with ItemSizingStrategy #33161

Merged

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Issue Description

RootCause

Description of Change

Issues Fixed

Tested the behaviour in the following platforms

Output Screenshot

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SuthiYuvaraj commented May 14, 2025 •

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