open and read x-callback-url using swift on MacOS

Question

I've figured out how to open an x-callback-url using the code below but I'm struggling to figure out how to read what is being sent back. Any thoughts appreciated:

 let BearURL = "bear://x-callback-url/add-text?title=notenane&text=somestuff&mode=append"

 if let checkURL = NSURL(string:  BearURL ) {
     if NSWorkspace.shared.open(checkURL as URL) {
         print("URL Successfully Opened for: \(BearURL)")
     }
 } else {
     print("Invalid URL: \(BearURL)")
 }