Uploading multiple files to Firebase Storage Very Slow - ios

Question

I am trying to upload two files to firebase storage at the same time. From what I understand this is not possible so what I did was try to upload one first and then the next file once the first is done.
It is working now, however the upload speed is very slow. Is this because of an issue with my code or is it because Im waiting for two uploads as opposed to one.
var index = 0
var urls = [String]()
fileprivate func uploadToServer(data: Any) {
if index == 0 {
let filename = NSUUID().uuidString
let storageRef = Storage.storage().reference().child("posts").child(filename)
storageRef.putData(data as! Data, metadata: nil) { (metadata, err) in
if let err = err {
self.navigationItem.rightBarButtonItem?.isEnabled = true
print("Failed to upload post image:", err)
self.showHUDwithError(error: err)
return
}
storageRef.downloadURL(completion: { (downloadURL, err) in
if let err = err {
print("Failed to fetch downloadURL:", err)
self.showHUDwithError(error: err)
return
}
guard let thisUrl = downloadURL?.absoluteString else { return }
self.urls.append(thisUrl)
self.index = self.index + 1
if self.type == "image" {
// we are done then so do the save to server call here
self.saveToDatabaseWithImageUrl()
} else {
self.uploadToServer(data: self.videoUrl as Any)
}
})
}
return
}
if index == 1 {
let filename = NSUUID().uuidString
let storageRef = Storage.storage().reference().child("posts").child(filename)
storageRef.putFile(from: data as! URL, metadata: nil) { (metadata, err) in
if let err = err {
self.navigationItem.rightBarButtonItem?.isEnabled = true
print("Failed to upload post image:", err)
self.showHUDwithError(error: err)
return
}
storageRef.downloadURL(completion: { (downloadURL, err) in
if let err = err {
print("Failed to fetch downloadURL:", err)
self.showHUDwithError(error: err)
return
}
guard let thisUrl = downloadURL?.absoluteString else { return }
self.urls.append(thisUrl)
self.saveToDatabaseWithImageUrl()
self.index = 0
})
}
}
}