Need Swift 5 (not 5.5) code sample - URLSession & Callback Handling

I have a Parent function which passes a UIImage to child function which makes a URLSession call and returns a string to the parent. I need the code where the parent function calls the child function and waits for a response before proceeding. I’m sure this is a basis code snippet for a Swift networking Pro but I don’t have any more time to spend on this. My attempts to use DispatchGroup() and completion handlers have not been successful. Code needs to run in xCode 12.5.1 (no 13 beta)