Restricting users to specified file types in Attachment control

This is a fairly straight-forward, but useful function to restrict users uploading attachments to file type specified. The example below restricts to JPG or PNG, but could be anything you choose. As soon as a non-allowed file is uploaded, it is immediately deleted and a message displayed regarding allowed file types. This code needs to go at OnAddFile in the Attachment control.

With(
   {
      _Type: 
      Last(
         Split(
            Last(Self.Attachments).Name,
            "."
         )
      ).Value
   },
   If(
      !(_Type in ["jpg", "png"]),
      Notify(
         "Only JPG or PNG files Allowed",
         Error
      );
      Reset(Self)
   )
)

You could also set a more prominent message label visibility off a variable triggered in the bottom If() statement if the Notification ribbon at the top is not sufficient.