prevent picking the same photo twice in UIImagePickerController

How do i prevent users from picking the same image twice in UIImagePickerContoroller to avoid duplication?

I tried doing it with the URLReference but its not working so I'm guessing its not the way.

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    if let url = info[UIImagePickerControllerReferenceURL] as? NSURL{
        if photosURL.contains(url){
             Utilities.showMessage(message: "photo Uploaded already", sender: self, title: ErrorTitle.FRIENDS, onDismissAction: nil)
        } else {
            if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
                photos.append(pickedImage)
            }
        }
    }
    dismiss(animated: true, completion: nil)
}

thanks,

Seems like you haven't appended the url to the photosURL? try this out:

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

if let url = info[UIImagePickerControllerReferenceURL] as? NSURL{
    if photosURL.contains(url){
         Utilities.showMessage(message: "photo Uploaded already", sender: self, title: ErrorTitle.FRIENDS, onDismissAction: nil)
    } else {
        photosURL.append(url)
        if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
            photos.append(pickedImage)
        }
    }
}
dismiss(animated: true, completion: nil)
}