I've found several sites with information on how this can be done, but none that seems to apply to Xcode 10.1 or iOS 12.1. The ones I've tried don't seem to work. I've tried this:
Create an empty swift project 'single view app'
Set the Signing Team to my Personal Team (Apple ID)
Set the active scheme to my connected (USB) iPhone 7 plus
Press the Play button
What I get is a 'Failed with exit code 1' and a horrendous log message.
My device turns up with a red frame in the active scheme dropdown list. What does that mean?
I'm running a MacBook Air with High Sierra. Any help is appreciated.