Fix macios filepicker #2981

matt-goldman · 2025-12-01T19:55:00Z

Description of Change

Updates the FileSaver maciOS implementation to use the new asCopy argument in the UIDocumentPickerViewController to tell the OS that you're saving a new file (not copying) when moving the temp file out of the sandobx to the users' desired location.

Linked Issues

Fixes [BUG] FileSaver iOS displays 'Move' instead of 'Save' #2336

PR Checklist

Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
Has tests (if omitted, state reason in description)
Has samples (if omitted, state reason in description)
Rebased on top of main at time of PR
Changes adhere to coding standard
Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

Only affects macOS and iOS. Screenshots show the resultant change on a physical iOS device:

bijington

Thanks Matt. LGTM!

Copilot

Pull request overview

This PR fixes a bug in the FileSaver implementation for macOS and iOS by correctly configuring the UIDocumentPickerViewController to treat the operation as saving a new file rather than copying an existing one.

Updates the UIDocumentPickerViewController constructor call to include the asCopy: true parameter
Ensures the OS properly handles moving temporary files to user-selected locations during save operations

VladislavAntonyuk · 2025-12-01T23:13:51Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

 		var tcs = taskCompetedSource = new(cancellationToken);

-		documentPickerViewController = new([fileUrl])
+		documentPickerViewController = new([fileUrl], true)


Should we delete temp file in this case if we copy it instead of move?

I think so. I started refactoring this, I wanted to see if I could make it a more logical flow, and added a Cleanup method that handled that and the dispose. But I didn't want to introduce too many changes.

Ideally if we don't use the temp file at all and write directly to the target location.

To make it simple for now you can wrap the code in try/finally block and delete temp file in finally section if it exists. It should not add complexity and many changes.

Ideally if we don't use the temp file at all and write directly to the target location.

I've spent a bit of time looking into this and I don't think it's practical. The only way to write directly outside the app's sandbox is using a security scoped URL and something like NSFileCoordinator. The problem is, this requires the user to grant access to it first, so it's not something we can do with a new file.

Additionally, we would have to track that the user has granted access and have safety checks that fall back to the temp file approach if not. And the problem with the first part is that it requires app-wide tracking and coordination. It's not impossible (far from it) but it's outside the scope of the vertical slice of this API.

The current approach (creating a temp file, then moving) is the canonical approach with Apple's API.

To make it simple for now you can wrap the code in try/finally block and delete temp file in finally section if it exists. It should not add complexity and many changes.

Agreed 🙂 Done in 47ddfe5. Please let me know if this is ok, or if you want me to make any other changes.

I made a tiny change to ensure the temp file is always deleted. Please let me know if it looks good

Looks good to me. I made a couple more changes, I updated the exception message wording a little, and moved the controller and event handler registration to address the comment below. I also updated the finally to delete the temp directory instead of the file, to avoid accumulation of orphaned guid-named directories.

Ensures temporary directory used by the file picker is always removed after the file selection is made, regardless of success or failure. Also improves error handling when a view controller cannot be retrieved. Fixes CommunityToolkit#2460

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

Ensures temporary directory used by the file picker is correctly removed on iOS. Moves the directory removal to the completion handler of the view controller presentation, ensuring it's executed after the picker is dismissed. Handles exceptions during file removal by re-throwing them after attempting to remove the temporary directory.

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

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

Copilot

Pull request overview

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

Copilot · 2025-12-06T21:01:54Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+		catch
 		{
-			throw new FileSaveException("Unable to get a window where to present the file saver UI.");
+			fileManager.Remove(tempDirectoryPath, out _);


The catch block doesn't handle cleanup of event handlers or dispose the document picker. If an exception occurs after the event handlers are attached (lines 44-45), these handlers will remain attached and could cause memory leaks or unexpected behavior in subsequent operations.

Consider calling InternalDispose() in the catch block to ensure proper cleanup of all resources.

Suggested change

fileManager.Remove(tempDirectoryPath, out _);

fileManager.Remove(tempDirectoryPath, out _);

InternalDispose();

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Move temp file removal to finally block to ensure cleanup always occurs. Remove redundant cleanup from view controller presentation callback.

Copilot

Pull request overview

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

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

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

Copilot

Pull request overview

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

Copilot · 2025-12-17T19:49:13Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+			documentPickerViewController.DidPickDocumentAtUrls += DocumentPickerViewControllerOnDidPickDocumentAtUrls;
+			documentPickerViewController.WasCancelled += DocumentPickerViewControllerOnWasCancelled;

-		var currentViewController = Platform.GetCurrentUIViewController();
-		if (currentViewController is not null)
-		{
-			currentViewController.PresentViewController(documentPickerViewController, true, null);
+			var currentViewController = Platform.GetCurrentUIViewController();
+			if (currentViewController is not null)
+			{
+				currentViewController.PresentViewController(documentPickerViewController, true, null);
+			}
+			else
+			{
+				throw new FileSaveException("Unable to get a window where to present the file saver UI.");
+			}


If an exception is thrown at line 54 (when currentViewController is null), the event handlers registered on lines 44-45 will not be cleaned up, potentially causing memory leaks. The documentPickerViewController won't be disposed either. Consider moving the event handler registration and view controller presentation inside a try-catch block, or ensure cleanup happens in the finally block by calling InternalDispose() when needed.

…essage, ensure temp directory is deleted (not just temp file)

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

Copilot · 2025-12-21T13:17:26Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+			taskCompetedSource?.TrySetCanceled(CancellationToken.None);
+			var tcs = taskCompetedSource = new(cancellationToken);
+
+			documentPickerViewController = new([fileUrl], true)


Consider using a named argument for the boolean parameter to improve code readability. The current code new([fileUrl], true) doesn't make it clear what true means. Using new([fileUrl], asCopy: true) would make the intent explicit that this parameter controls whether the operation should be treated as a copy/save operation rather than just opening/referencing the file.

Suggested change

documentPickerViewController = new([fileUrl], true)

documentPickerViewController = new([fileUrl], asCopy: true)

Copilot · 2025-12-21T13:17:27Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+public sealed partial class FileSaverImplementation : IFileSaver
 {
-	UIDocumentPickerViewController? documentPickerViewController;
 	TaskCompletionSource<string>? taskCompetedSource;


The field name "taskCompetedSource" contains a typo - it should be "taskCompletedSource" (missing 'l'). This typo is carried over from existing code but should be corrected for clarity and professionalism.

Copilot

Pull request overview

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

Copilot · 2025-12-21T13:24:13Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+public sealed partial class FileSaverImplementation : IFileSaver
 {
-	UIDocumentPickerViewController? documentPickerViewController;
 	TaskCompletionSource<string>? taskCompetedSource;


The field name has a typo: "taskCompetedSource" should be "taskCompletedSource" (missing 'l' in 'Completed').

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

Copilot · 2025-12-21T13:44:44Z

src/CommunityToolkit.Maui.Core/Essentials/FolderPicker/FolderPickerImplementation.macios.cs

-		AllowsMultipleSelection = false
-	};
-
 	TaskCompletionSource<Folder>? taskCompetedSource;


The field name 'taskCompetedSource' contains a spelling error. It should be 'taskCompletedSource' to match the corrected spelling in FileSaverImplementation.macios.cs. This typo exists in all usages throughout the file (lines 13, 20, 21, 54, 60).

Copilot · 2025-12-21T13:44:45Z

src/CommunityToolkit.Maui.Core/Essentials/FolderPicker/FolderPickerImplementation.macios.cs

+		documentPickerViewController.DidPickDocumentAtUrls += DocumentPickerViewControllerOnDidPickDocumentAtUrls;
+		documentPickerViewController.WasCancelled += DocumentPickerViewControllerOnWasCancelled;


There's a potential race condition: the event handlers (DocumentPickerViewControllerOnDidPickDocumentAtUrls and DocumentPickerViewControllerOnWasCancelled) reference the field 'taskCompetedSource', but this field could be modified by a subsequent call to InternalPickAsync before the event handlers fire. If InternalPickAsync is called again while a previous operation is still pending, the new TaskCompletionSource will overwrite the field at line 21, causing the first operation's event handlers to complete the wrong task.

Consider capturing the TaskCompletionSource in a local variable and using that local variable in the event handlers to avoid this race condition. This would require using lambda expressions instead of method references for the event handlers.

Copilot · 2025-12-21T13:44:45Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

 	void DocumentPickerViewControllerOnDidPickDocumentAtUrls(object? sender, UIDocumentPickedAtUrlsEventArgs e)
 	{
-		try
+		if (e.Urls.Length == 0)


The fallback to 'e.Urls[0].ToString()' may not provide the correct file path format expected by callers. The original code threw a FileSaveException when Path was null, which is more explicit about the failure. Using ToString() as a fallback could return a URL string (e.g., "file:///path/to/file") instead of a file system path, which may cause issues for consumers expecting a standard file path.

Consider whether this fallback is intentional and correct, or if throwing an exception (as in the original code) would be more appropriate to maintain consistency with the error handling pattern used elsewhere (e.g., line 59 in FolderPickerImplementation which still throws when Path is null).

Copilot · 2025-12-21T13:44:45Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

-
-		documentPickerViewController = new([fileUrl])
+		await WriteStream(stream, fileUrl.Path ?? throw new FileSaveException("Path cannot be null."), progress, cancellationToken);
+		UIDocumentPickerViewController? documentPickerViewController = new([fileUrl], true)


The nullable annotation '?' on documentPickerViewController is unnecessary since the variable is immediately initialized and never assigned null. The variable should be declared as non-nullable: 'UIDocumentPickerViewController documentPickerViewController'.

Suggested change

UIDocumentPickerViewController? documentPickerViewController = new([fileUrl], true)

UIDocumentPickerViewController documentPickerViewController = new([fileUrl], true)

Copilot · 2025-12-21T13:44:45Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs

+		{
+			throw new FileSaveException("Cannot present file picker: No active view controller found. Ensure the app is active with a visible window.");
+		}
+


There's trailing whitespace at the end of this line. Consider removing it for consistency with the codebase formatting standards.

Copilot · 2025-12-21T13:44:46Z

src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverImplementation.macios.cs


+		taskCompletedSource?.TrySetCanceled(CancellationToken.None);
+		var tcs = taskCompletedSource = new(cancellationToken);
+


There's trailing whitespace at the end of this line. Consider removing it for consistency with the codebase formatting standards.

matt-goldman added 2 commits December 2, 2025 06:24

Test file saver with export to service mode

4d9487c

Used correct constructor with asCopy set to true

ed5f254

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Add temporary directory cleanup in file saving process

47ddfe5

matt-goldman dismissed bijington’s stale review via 47ddfe5 December 2, 2025 06:36

Fixes disposal of temporary file on iOS

07be3c6

Ensures temporary directory used by the file picker is always removed after the file selection is made, regardless of success or failure. Also improves error handling when a view controller cannot be retrieved. Fixes CommunityToolkit#2460

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Merge branch 'main' into fix-macios-filepicker

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Update src/CommunityToolkit.Maui.Core/Essentials/FileSaver/FileSaverI…

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Merge branch 'main' into fix-macios-filepicker

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Merge branch 'main' into fix-macios-filepicker

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Merge branch 'main' into fix-macios-filepicker

9b6b6ad

Refactor temp file cleanup in FileSaver (macOS/iOS)

2f2189a

Move temp file removal to finally block to ensure cleanup always occurs. Remove redundant cleanup from view controller presentation callback.

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Ensure resources are only created if UI is available, improve error m…

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…essage, ensure temp directory is deleted (not just temp file)

Move dispose to finally

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fix naming

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fix order

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check for index

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rework File/FolderPicker. Removed IDisposable, Added IsCancelled

17c909d

	fileManager.Remove(tempDirectoryPath, out _);
	fileManager.Remove(tempDirectoryPath, out _);
	InternalDispose();

	documentPickerViewController = new([fileUrl], true)
	documentPickerViewController = new([fileUrl], asCopy: true)

		documentPickerViewController.DidPickDocumentAtUrls += DocumentPickerViewControllerOnDidPickDocumentAtUrls;
		documentPickerViewController.WasCancelled += DocumentPickerViewControllerOnWasCancelled;

	UIDocumentPickerViewController? documentPickerViewController = new([fileUrl], true)
	UIDocumentPickerViewController documentPickerViewController = new([fileUrl], true)


		taskCompletedSource?.TrySetCanceled(CancellationToken.None);
		var tcs = taskCompletedSource = new(cancellationToken);

Fix macios filepicker #2981

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Fix macios filepicker #2981

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Description of Change

Linked Issues

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matt-goldman commented Dec 1, 2025 •

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