Thank you so much for the detailed explanation, and for the idea of a short-term solution. I have filed a report: FB22138371 and in the meantime I'm using my_system(command.decomposedStringWithCanonicalMapping) instead of my_system(command) in my apps.

The short answer is that I tried everything (I could think of) and everything I tried fails. in the Files app, simple tap on the file: opens QuickLook (iOS 16) or the Preview app (iOS 26) for files without diacritics in their name. Doesn't do anything for files with diacritics (it's like I didn't tap on the file at all). in the Files app, long press on the file to get the contextual menu, scroll to Quick Look ("Coup d'œil" since I'm still in a non-English language), I get a blank screen that says "Document PDF". opening the file using the documents browser from the Preview app (iOS 26) or PDF Viewer (iOS 26, iOS 16): does not display the file (it's like I didn't tap at all). previewing the file from inside the app using UIDocumentInteractionController(url: url).presentPreview(animated: false): blank screen that says "Document PDF". opening the file by calling another app from inside the app using an UIActivityViewController: nothing happens on iOS 26, I get the error message ("You do not have permission to save the file "filename.pdf" in the folder "myFolder"") with PDF Viewer on iOS 16.

Update: enabling auto-correction specifically for that keyboard and only for that keyboard seems to work. But I'd still love to know more about that keyboard: is that the only solution? the recommended solution?

Ah, yes I can also confirm that the extension is killed by the system after exactly 5 seconds. I was wondering why it was being killed (memory use? access to forbidden resources?) but I hadn't thought of time limits.

Thank you so much for the detailed, step-by-step instructions. I have now also uploaded a build to the AppStore, with an in-app extension. The key step that I had missed in my previous attempts is number 3 on your list: "remove the Info.plist for the Extension that was generated by Xcode" (and probably number 4, "delete the INFOPLIST_FILE in build Settings"). The extension is not yet doing what I want it to, but that's another problem. I can upload, so it's worth pursuing this line of work.

Thanks for that. I don't think it should change anything, but what I'm trying to do uses ExtentionFoundation, not ExtensionKit (so without a graphical user interface for the extension).

Hi, in case another developer tries to add extensions to an iOS app, I received the following answer through Feedback: What you are attempting to do is not supported. We recommend that you use the XPC framework for similar capabilities: https://developer.apple.com/documentation/xpc

Yes, one of them was by mistake; I could not find a way to delete the message.

Thanks for the recommendation; I've added extra information. Basically my main concern is to isolate unstable code to make the app more stable, but also extensions are running as separate process, which would allow me to add a lot more commands to the terminal app. I also have potential uses in mind if there is no memory limit, and if we can share extensions between apps, but I think these are hills too large to climb at the moment.

Thank you very much for this detailed answer; that explains a lot of things. Yes, my goal is to run iOS extensions that are specifically for my app's usage, not shared with any other app. I've submitted FB20710338

Thank you for your answer. I tried with both "AsheKube.app.a-Shell.localWebServer" and "com.example.example-extension". The only difference I could see is that sometimes it would fail when uploading (I would get the error message inside Xcode) and other time it would fail after uploading: I would get a kind e-mail from AppStore Connect, stating: Hello, We noticed one or more issues with a recent delivery for the following app: a-Shell App Apple ID 1473805438 Version 1.17.0 Build 500 Please correct the following issues and upload a new binary to App Store Connect. ITMS-90349: Invalid Info.plist value - The value of the EXExtensionPointIdentifier key, AsheKube.app.a-Shell.localWebServer, in the Info.plist of “a-Shell.app/Extensions/localWebServer.appex” is invalid. Please refer to the App Extension Programming Guide at https://developer.apple.com/library/content/documentation/General/Conceptual/ExtensibilityPG/Action.html#/apple_ref/doc/uid/TP40014214-CH13-SW1. Apple Developer Relations Builds 496, 497 and 500 are builds that I managed to upload, but were not approved. Builds 501 and 502 are approved because I gave up, removed all extension code from the app and moved on to other features (and apparently builds 498 and 499 are builds that I could not upload, where it failed inside Xcode).

And to answer the second question, the proper value for the "EXExtensionPointIdentifier" key seems to be: "com.example.example-extension"

Answering my own question: the extension is running separately, in order to see breakpoints or calls to NSLog, I need to start the extension in XCode, not the main app.

This might help: although there are no issues on Xcode, when I upload the app I get the following error: Validation failed Invalid Info.plist value. The value of the EXExtensionPointIdentifier key, AsheKube.app.a-Shell.localWebServer, in the Info.plist of “a-Shell.app/Extensions/localWebServer.appex” is invalid. Please refer to the App Extension Programming Guide at https://developer.apple.com/library/content/documentation/General/Conceptual/ExtensibilityPG/Action.html#/apple_ref/doc/uid/TP40014214-CH13-SW1. (ID: 35ef96bf-3831-466e-b793-4bbd69f5c0c5) Unfortunately, there is nothing on the linked web page about ExtensionFoundation or about what should be in the Info.plistfile.

In case other developers encounter the same issue, I found out by accident that I can force the toolbar to check the status of its buttons by adding an extra button, then removing it: if #available(iOS 26, *) { self.editorToolbar.items?.append(UIBarButtonItem(title: "Hi", style: .plain, target: self, action: nil)) self.editorToolbar.items?.removeLast() } With this change, the buttons that were hidden become apparent again. Now I have the issue that the longPressGesture is not called on the buttons that were temporarily hidden...