问题
Here is my scenario. In my app there is no need of continuously monitoring user location, but I need the location to be as accurate as possible. So I just call CLLocationManager startUpdatingLocation with kCLLocationAccuracyBestForNavigation set as desiredAccuracy, and after I get the location with my desired accuracy (by comparing newLocation.horizontalAccuracy with predefined value) I want to stop the location update and revoke update again after several seconds. But when I call stopUpdatingLocation the location icon from status bar disappears after about 10 seconds, does this mean that apple has considered this scenario, when user calls stopUpdatingLocation it doesn't shut down antenas for some period of time, may be because turning them back on is somewhat expensive in terms of energy, so they just wait some time and only after that shut down antenas. Or may be simply the location icon is not disappeared but the antenas are turned off. So can someone explain what happens exactly when someone calls stopUpdatingLocation?
回答1:
The GPS radios power down 10 seconds after last use. That was discussed in one of the performance optimization sessions at WWDC.
来源：https://stackoverflow.com/questions/15875274/does-the-internal-gps-antenas-stop-working-immediately-after-calling-cllocationm