File Provider Extension trouble

Hi everyone,

I am a beginner in iOS/Swift programming. I'm trying to develop a mobile application that allows to mount a network drive in the iphone Files application via the WebDav protocol.

I saw on the internet that WebDav is no longer implemented in iOS because considered deprecated by apple.

To accomplish this task, I decided to separate responsibilities as follows:

Framework:

• WebDav (responsible for communication with the WebDav server)

FileProviderExtension:

• FileBridge (Responsible for bridging the gap between the WebDav Framework and the iOS Files app)

Main App

I also have an AppGroup that includes the main application and the fileproviderextension

Initially, to measure the feasibility and complexity of this task, I'd like to make a simplistic version that simply displays the files on my drive in the Files app, without necessarily being able to interact with them.

FileProviderExtension.swift:

import FileProvider
import WebDav

class FileProviderExtension: NSObject, NSFileProviderReplicatedExtension {
    private var webDavService: WebDavService?

    required init(domain: NSFileProviderDomain)
    {
        super.init()
        self.webDavService = WebDavService(baseURL: URL(string: "https://www.mydrive.com/drive")!)
    }
    
    func invalidate() {
        // TODO: cleanup any resources
    }
    
    func item(for identifier: NSFileProviderItemIdentifier,
              request: NSFileProviderRequest,
              completionHandler: @escaping (NSFileProviderItem?, Error?) -> Void) -> Progress {
        let progress = Progress(totalUnitCount: 1)
        
        Task {
            do {
                if let items = try await webDavService?.propfind(path: identifier.rawValue, depth: 1),
                   let item = items.first(where: { $0.itemIdentifier == identifier }) {
                    completionHandler(item, nil)
                } else {
                    completionHandler(nil, NSError(domain: NSCocoaErrorDomain,
                                                   code: NSFileNoSuchFileError,
                                                   userInfo: nil))
                }
            } catch {
                completionHandler(nil, error)
            }
        }
        
        return progress
    }
    
    func fetchContents(for itemIdentifier: NSFileProviderItemIdentifier,
                       version requestedVersion: NSFileProviderItemVersion?,
                       request: NSFileProviderRequest,
                       completionHandler: @escaping (URL?, NSFileProviderItem?, Error?) -> Void) -> Progress {
        let progress = Progress(totalUnitCount: 1)
        
        Task {
            do {
                guard let service = webDavService else {
                    throw WebDavError.invalidResponse
                }
                
                let data = try await service.get(fileAt: itemIdentifier.rawValue)
                let tempURL = FileManager.default.temporaryDirectory.appendingPathComponent(itemIdentifier.rawValue)
                try data.write(to: tempURL)
                
                completionHandler(tempURL, nil, nil)
            } catch {
                completionHandler(nil, nil, error)
            }
        }
        
        return progress
    }
    
    func createItem(basedOn itemTemplate: NSFileProviderItem, fields: NSFileProviderItemFields, contents url: URL?, options: NSFileProviderCreateItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (NSFileProviderItem?, NSFileProviderItemFields, Bool, Error?) -> Void) -> Progress {
        // TODO: a new item was created on disk, process the item's creation
        
        completionHandler(itemTemplate, [], false, nil)
        return Progress()
    }
    
    func modifyItem(_ item: NSFileProviderItem, baseVersion version: NSFileProviderItemVersion, changedFields: NSFileProviderItemFields, contents newContents: URL?, options: NSFileProviderModifyItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (NSFileProviderItem?, NSFileProviderItemFields, Bool, Error?) -> Void) -> Progress {
        // TODO: an item was modified on disk, process the item's modification
        
        completionHandler(nil, [], false, NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:]))
        return Progress()
    }
    
    func deleteItem(identifier: NSFileProviderItemIdentifier, baseVersion version: NSFileProviderItemVersion, options: NSFileProviderDeleteItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (Error?) -> Void) -> Progress {
        // TODO: an item was deleted on disk, process the item's deletion
        
        completionHandler(NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:]))
        return Progress()
    }
    
    func enumerator(for containerItemIdentifier: NSFileProviderItemIdentifier,
                    request: NSFileProviderRequest) throws -> NSFileProviderEnumerator {
        return FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier,
                                      service: webDavService)
    }
}

Here's the code I use to initialize my domain in the main app files:

fileprivate func registerFileProviderDomain() {
        let domainIdentifier = NSFileProviderDomainIdentifier("FileProviderExtension Bundle Identifier")
        let domain = NSFileProviderDomain(identifier: domainIdentifier,
                                          displayName: "My Drive")

        NSFileProviderManager.add(domain) { error in
            NSFileProviderManager.add(domain) { error in
            if let error = error {
                print("Error cannot add domain file provider : \(error.localizedDescription)")
            } else {
                print("Success domain file provider added")
            }
        }       
    }

I can't get rid of the Error : Error cannot add domain file provider : The operation couldn’t be completed. Invalid argument.

I don't know what I'm missing Please help me understand