问题
My app registers for background location updates (not Significant Change. I need more granularity than kilometers)
That part works fine. I just want to stop the updates after the app has been in the background for 60 minutes. The way I'm doing it right now is to call stopUpdatingLocation in my CLLocationManager delegate.
However, I am unsure if this will actually stop my app from receiving background location updates, or if it will, but will just ignore them. Ideally, I'd like to not have my app be responsible for battery drain except for a small period of time after user activity.
Apple's documentation tends to send me in circles on this one. Right when I think "Executing Code in the Background" is about to spill the answer, it directs me to "Location Awareness Programming Guide." Right when that one is about to get specific about this question, it sends me back to "Executing Code in the Background." :)
回答1:
I'm not sure whether your app has total control over this, but the docs for stopUpdatingLocation do state the following ...
Disabling event delivery gives the receiver the option of disabling the appropriate hardware (and thereby saving power) when no clients need location data
Which would suggest that should your app be the only one requesting background location data, and you request it to stop the GPS receiver would disable the appropriate hardware to save on power, which I think it was you're looking for.
What I can suggest is that you enable Power logging in Settings -> Developer, then run your app for an hour or so to a point where you think GPS is disabled, run for another hour and then compare the power usage in Instruments. This should provide you with a much clearer picture.
回答2:
Calling stopUpdatingLocation will indeed stop GPS and so on, but if you place this call inside locationManager:didUpdateToLocation:fromLocation of your CLLocationManager delegate, then it might never be called.
Keep in mind that this method is only executed whenever a more accurate position or a (according to the active distance filter) significantly different position is available. If the device does not move at all and if the circumstances affecting the accuracy also do not change, it may not be called for hours (I have verified it for several minutes myself) and GPS will also stay enabled for this long.
For apps that only work in the foreground, you can use an NSTimer of 60minutes, but for apps that run in the background, the closest to a working solution that I have found so far, is a scheduled UILocalNotification. But even that requires the user to confirm an alert, before the app is restarted and able to turn the GPS off.
Maybe beginBackgroundTaskWithExpirationHandler: is the key to a better solution, but I have not completely figured it out, yet.
来源：https://stackoverflow.com/questions/6689296/stopping-corelocation-background-updates