FilePicker returns null when running iOS app on macOS (not Catalyst)

[follesoe]

Description

When using the FilePicker API in an iOS application, the PickAsync method returns null (as if canceled) even if the user has not canceled or picked a file.

The same behavior exists in the old Xamarin.Essentials library. On macOS Catalyst, I believe you have worked around the problem by adding in #if !MACCATALYST here: https://github.com/dotnet/maui/blob/main/src/Essentials/src/FilePicker/FilePicker.ios.cs#L41 - which is not present in https://github.com/xamarin/Essentials/blob/main/Xamarin.Essentials/FilePicker/FilePicker.ios.cs#L35

However, I believe we are getting the "macOS Catalyst" behavior of the UIDocumentPickerViewController when an iOS app runs on an M-series Mac.

One possible solution is using NSProcessInfo.ProcessInfo.IsiOSApplicationOnMac; to detect if the iOS app runs on macOS:

#if !MACCATALYST
			if (documentPicker.PresentationController != null && !NSProcessInfo.ProcessInfo.IsiOSApplicationOnMac)
			{
				documentPicker.PresentationController.Delegate =
					new UIPresentationControllerDelegate(() => GetFileResults(null, tcs));
			}
#endif

Steps to Reproduce

1. Create a new MAUI application using the FilePicker API
2. Build for iOS and distribute the app through TestFlight (unfortunately MAUI does not support running iOS apps on macOS directly as per: How to test on Mac (Designed for iPad) or Apple Vision pro? xamarin/xamarin-macios#20868)
3. See that PickAsync returns null even if file picker is not dismissed.

Link to public reproduction project repository

No response

Version with bug

9.0.0-rc.2.24503.2

Is this a regression from previous behavior?

No, this is something new

Last version that worked well

Unknown/Other

Affected platforms

iOS

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[similar-issues-ai]

We've found some similar issues:

• FilePicker on MacCatalyst app is not working (occasionally) #15126 , similarity score: 85%
• FilePicker on MacOs (MacCatalyst) returns null #20741 , similarity score: 84%
• FilePicker Does not show in Mac Catalyst #20994 , similarity score: 81%

If any of the above are duplicates, please consider closing this issue out and adding additional context in the original issue.

Note: You can give me feedback by 👍 or 👎 this comment.

[follesoe]

The issues reported by the simular-issues-ai are all relevant but do not cover this case, as they focus on Mac Catalyst, while I believe the same bug exists when running iOS apps that are not Catalyst on macOS.