[iOS] Fixed issue where group Header/Footer template was set to all items when IsGrouped was true for an ObservableCollection

[Tamilarasan-Paranthaman]

Issue 1: The group header and footer templates were not updating correctly when set at runtime.

Root Cause of the issue

• The mapper for the group header and footer templates was not implemented to support dynamic updates at runtime. As a result, changes made to the templates during runtime had no effect, and the templates were not displayed as expected.

Description of Change

• Implemented a mapper for the group header and footer templates to enable dynamic updates at runtime. This resolves the issue.

Issue 2: After implementing the mapper for the group header and footer templates, those templates were incorrectly applied to all items when IsGrouped was set to true for an ObservableCollection.

Root Cause of the issue

• Items in the ItemsSource collection were being cast to IEnumerable and added to the groups collection, even if they were not actually of an IEnumerable type. The number of sections (NumberOfSections) was determined based on the count of this incorrectly formed collection, leading to incorrect template application and section configuration.

Description of Change

• Added a type check to ensure that only items implementing IEnumerable are treated as sections when updating the NumberOfSections count. Non-IEnumerable items are no longer considered as grouped sections. As a result, NumberOfSections now correctly reflects the actual grouping structure.

Issues Fixed

Fixes #29141

Test Case

• The test case for this fix has already been added in the following PR. Once the PR is merged, we’ll be able to validate it on iOS as well.
• [Android] Fixed issue where group Header/Footer template was applied to all items when IsGrouped was true for an ObservableCollection #28886

Tested the behaviour in the following platforms

• iOS
• Android
• Mac
• Windows

Screenshot

Before Fix	After Fix
Before-fix.mov	After-Fix.mov

[dotnet-policy-service]

Hey there @@Tamilarasan-Paranthaman! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[Copilot]

Pull Request Overview

This PR fixes the issue where group header and footer templates were incorrectly applied and not updating as expected when the ObservableCollection’s IsGrouped property was true.

• Adds group header/footer template mappings for iOS in CollectionViewHandler2.iOS.cs.
• Updates ObservableGroupedSource.cs to only add groups that implement IEnumerable.
• Removes platform-specific mapping conditions in GroupableItemsViewHandler.cs.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Controls/src/Core/Handlers/Items2/CollectionViewHandler2.iOS.cs	Adds new mapping for group header/footer templates to support dynamic updates on iOS.
src/Controls/src/Core/Handlers/Items/iOS/ObservableGroupedSource.cs	Adjusts group source creation with a type-check to include only IEnumerable groups.
src/Controls/src/Core/Handlers/Items/GroupableItemsViewHandler.cs	Removes conditional mapping for group header/footer templates on certain platforms.

[Copilot]

The check 'if (group is IEnumerable enumerable)' may inadvertently treat strings as groups. Consider excluding strings (e.g., 'if (group is IEnumerable enumerable && !(group is string))') to prevent unintended behavior.

Suggested change

	if (group is IEnumerable enumerable)
	if (group is IEnumerable enumerable && !(group is string))

[jsuarezruiz]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jsuarezruiz]

There are some related tests failing on iOS and Mac:

Could you review if are related with the changes?

[Tamilarasan-Paranthaman]

There are some related tests failing on iOS and Mac: Could you review if are related with the changes?

@jsuarezruiz , yes, the failures were caused by these changes. I have updated the fix and committed the changes. Could you please review them and let me know if you have any concerns?

[jsuarezruiz]

/azp run MAUI-UITests-public

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Azure Pipelines successfully started running 1 pipeline(s).