Firebase Storage Warning: downloadURL()' is deprecated: Use `StorageReference.downloadURLWithCompletion()

Question

I just updated my project to the latest version of Firebase Storage and I am now getting a warning: downloadURL() is deprecated: Use StorageReference.downloadURLWithCompletion() to obtain a current download URL.

I looked at the Firebase image upload documentation but it still references using downloadURL() which is now depreciated. In the code below I am getting the download URL of the image as a String. The code works but now to be updated since downloadURL() is depreciated

uploadProfilePicTask.observe(.success) { snapshot in

  guard let profilePicStringURL = snapshot.metadata?.downloadURL()?.absoluteString else { return }
  ...

Here is my attempted updated. I tried the code below with the new downloadURLWithCompletion() but something in snapshot.metadata?.storageReference? is returning nil so I am not able to retrieve the url String. Does anyone know how to use the new downloadURLWithCompletion() appropriately below?

uploadProfilePicTask.observe(.success) { snapshot in
  snapshot.metadata?.storageReference?.downloadURL { URL, error in
    if let urlString = URL?.absoluteString {
      // Do something
    } else {
      return
    }
  }

Answer 1

Basically not using the metadata but instead just getting the url after the success of your observe event. Since it's successful and you know it's there, you can download the URL. It's there in their docs to 'Generate a download URL'. Below, I'm assuming your StorageReference is uploadProfilePicTask.

uploadProfilePicTask.downloadURL(completion: { (url, error) in
                    if (error == nil) {
                        if let downloadUrl = url {
                           // Make you download string
                           let downloadString = downloadUrl.absoluteString
                        }
                    } else {
                   // Do something if error
                    }
           })