You can query the shared CLLocationManager instance if the location service is enabled. The correct way is to respect the users choice to disable location services.
But if you want to, just start the location service anyway and the user will be prompted to start it again. If the user opts in on the request locations will begin to be reported on your delegate as usual. If the user instead denies your request you will get a failure callback to the locationManager:didFailWithError: delegate method. The error will have an error code of kCLErrorDenied.
I would strongly discourage you from doing this, but you can try to start the service again if the user says no, and the user will be asked again. Most users will hate you for it though.
+1 the user should only decide whether they want to allow an app to use their location at one point, ive noticed a lot of apps ive used recently request permission regularly, even if it hasnt been allowed in the past, which im not a fan of
agree. if your app relies on location services for any significant functionality, the nice way to do this is to detect when location services are disabled and present passive UI in your app that notifies users and allows them to turn location services back on. If a user opts in you can then start location services which will prompt the user to enable.
Thanks for your feedback. I am with you and totally do not want to annoy my users be re-asking them to allow my application access to location services. But in this case, the user is tapping on the "get current location" button, so it seems appropriate to tell them that they need to turn this on. This is the same as in the Map application when the user taps on the "get current location" button. I am doing as you suggest, calling the start monitor method, but it does not re-prompt the user, I just get the kCLErrorDenied error.
This is incorrect. Once the location services authorization alert view is presented, users will never see it again. Ever. (Notwithstanding a phone reset.) Even an app delete and reinstall will not present it again. The only way a user can restore location service authorization is to go to the Settings app and re-enable it directly.