Couldn't get files contents on a real device (swift file base app)

I have a file based app that opens source code. Here is the function that I use for it.

func presentDocument(at documentURL: URL) {
    
    let storyBoard = UIStoryboard(name: "Main", bundle: nil)
    let documentViewNavController = storyBoard.instantiateViewController(withIdentifier: "documentNavVc")
    
    do {
        
        let text =  try String(contentsOf: documentURL, encoding: .utf8)
        let name = documentURL.lastPathComponent
        if let documentViewController = documentViewNavController.contents as? DocumentViewController{
            documentViewController.text = text
            documentViewController.title = name
        }
        
    }
    catch {
        print(error.localizedDescription)
    }
    
    documentViewNavController.modalPresentationStyle = .fullScreen
    
    present(documentViewNavController, animated: true, completion: nil)
}

}

so the issue is that on a simulator it works perfectly, but on a real device, it gets to catch block after it tries to get contents of the file and prints this error: The file couldn’t be opened because you don’t have permission to view it.

Maybe its because I don't ask the permission of the user to use the file browser (I don't know)

Any solution here?

So the solution was to open secured files (all files, except ones you have in your app folder are secured) and this article helped me https://developer.apple.com/documentation/uikit/view_controllers/providing_access_to_directories