File sharing between main app and share extension works on simulator but fails on device

Question

I developed an app with a share extension, and want to receive files shared from other apps by the share extension.

It works fine on simulator, but get an error like below if I read the shared data (using Data(contentsOf: url)) when runs on device.

Failed to read file, error Error Domain=NSCocoaErrorDomain Code=257 "The file “[File name]” couldn’t be opened because you don’t have permission to view it." UserInfo={NSFilePath=/private/var/mobile/Containers/Shared/AppGroup/[some ID String]/File Provider Storage/[File name], NSUnderlyingError=0x2800b42a0 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}

The following is what I do in the share extension.

        
        let attachments = (self.extensionContext?.inputItems.first as? NSExtensionItem)?.attachments ?? []
        
        guard #available(iOSApplicationExtension 14.0, *) else {
            return
        }
        
        let contentType = "public.file-url"
        for provider in attachments {
              guard provider.hasItemConformingToTypeIdentifier(contentType)
              else { continue }
                            
              provider.loadItem(forTypeIdentifier: contentType,
                                options: nil) { [unowned self] (data, error) in
                   
              let url = data as! URL





           // Get the permission error here
           // if run on device
              try? Data(contentsOf: url) 
           

            }
        }
        self.extensionContext?.completeRequest(returningItems: [], completionHandler: nil)

I am running this code on an iPhone 12, iOS 15.3.1. Xcode 13.4.1.

If any further information is needed, please let me know.

Thank you.