Question: my application just get the text from the clipboard and set it into a listbox
and I need to save the items of listbox for next lunch
I've used this code for that

```
StreamWriter SaveFile = new StreamWriter(sPath);
numlastline = listBox1.Items.Count-1;
SaveFile.WriteLine(listBox1.Items[numlastline]);
SaveFile.ToString();
SaveFile.Close();

```

but its only save the last clip to the text and delet the Previous ones

Answer: 
The error says that `downloadURL` has no return value. It uses a completion handler to return data from an asynchronous task

I'm not familiar with Firebase but the syntax of the API seems to be

```
metadata?.storageReference?.downloadURL( completion: { (url, error) in
    let changeRequestPhoto = user?.user.createProfileChangeRequest()
    changeRequestPhoto?.photoURL = url
    changeRequestPhoto?.commitChanges(completion: { error in
        if let error = error {
            print (error.localizedDescription)
            return
        }
        else {
            print ("Sweet!")
        }
    })
})

```
On the first line, I'm assuming `self.fileURL` is the `String` you're referencing, but you are attempting to assign to it the output of `metadata?.storageReference?.downloadURL` which returns `Void`. 

You'll need to grab the `url` from the completion block, as seen below. Note, this example is taken directly from [Firebase's documentation](https://firebase.google.com/docs/storage/ios/download-files#generate_a_download_url)

```
starsRef.downloadURL { url, error in
  if let error = error {
    // Handle any errors
  } else {
    // Get the download URL for 'images/stars.jpg'
  }
}

```