Saving File Manager video url to Core Data

Hello community!
I made an app, where the user can add videos from their photo library and they are copied into the app, where they are displayed. A PHpicker gets the video from the library and copies it to the documents-directory of the app, then returns the url, showing where it is saved, as a string. That url -string is then saved in core data and retrieved in order to watch the video, in a video player. This all works really well, until the app is rebuilt, because then the url saved to core data doesn’t lead to the video anymore.

It is basically this problem:

So my question: How can I save some kind of key in core data, that always returns me the right url to that video, instead of saving the url directly? I wasn’t able to implement the Stack overflow solutions, sorry about that /: , that’s why I am asking here. The code for the picker and saving the url to core data is below:

Picker:

import SwiftUI
import UIKit
import PhotosUI

struct VideoPicker: UIViewControllerRepresentable{
    @Binding var videoURL:String?
    
    
    func makeUIViewController(context: Context) -> PHPickerViewController {
        
        var config = PHPickerConfiguration()
        config.filter = .videos
        let picker = PHPickerViewController(configuration: config)
        picker.delegate = context.coordinator
        return picker
    }
    
    func updateUIViewController(_ uiViewController: PHPickerViewController, context: Context) {}
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator:NSObject, PHPickerViewControllerDelegate{
        
        
        
        let parent:VideoPicker
        init(_ parent: VideoPicker){
            
            self.parent = parent
        }
        
        func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
            picker.dismiss(animated: true) {
                // do something on dismiss
            }
            
            guard let provider = results.first?.itemProvider else {return}
            provider.loadFileRepresentation(forTypeIdentifier: "public.movie") { url, error in
                guard error == nil else{
                    print("error in video picker")
                    return
                }
                // receiving the video-local-URL / filepath
                guard let url = url else {
                    print("error 2 in video picker")
                    return
                }
                // create a new filename
                let fileName = "\(Int(Date().timeIntervalSince1970)).\(url.pathExtension)"
                // create new URL
                let newUrl = URL(fileURLWithPath: NSTemporaryDirectory() + fileName)
                // copy item to APP Storage
                try? FileManager.default.copyItem(at: url, to: newUrl)
                self.parent.videoURL = newUrl.absoluteString
                print("video added")
            }
        }

    }
}

Core Data Save:


//exercise.videoUrls is an array of strings, 
func saveVideo( url: String){
        if exercise.videoUrls != nil{

              exercise.videoUrls!.append(url)
              try! viewContext.save()
            
        } else {
            exercise.videoUrls =  [url]
            try! viewContext.save()
        }