how to request auth for CLLocationManager on macOS

According to the Core Location Best Practices WWDC 2016 session,

For macOS, we only support always authorization. Furthermore, Core Location will automatically display a prompt when you attempt to access location information.

You don't need to call requestAlwaysAuthorization on macOS.

Don't forget to turn on "Location" under the "App Sandbox" capability for your target. Also, in my tests, the prompt was only shown the first time the app was run.