I tried “Add GPX file to Project” in Xcode in the Debug > Simulate Location menu. I chose my file and clicked to proceed. The dialog box disappeared but nothing else seemed to have happened.
What did work for me was dragging and dropping a GPX file on to the project (in the panel showing list of files in fact). I went to https://gpxgenerator.com/ and generated a GPX file there. I stripped out the elevation and time and saved the file. Then I dropped that file into my Xcode project. The name of the location shown in the menu seems to be derived by Xcode from the filename of the GPX.
I had a file called addenbrookes.gpx:
<?xml version="1.0"?> <gpx version="1.1" creator="gpxgenerator.com"> <wpt lat="52.17563249587351" lon="0.1436939835548401"></wpt> </gpx>
After I added that the menu for “Simulate Location” includes “addenbrookes” as an option for a location to choose.