Summary:
In the yet-to-be-released iOS 11, Apple has changed the way they notify the user of location services. (You can watch their session from WWDC about all the changes [here](https://developer.apple.com/videos/play/wwdc2017/713/).)
The current implementation of `RCTLocationObserver` uses the standard location services from Apple. When the user has granted `Always` location permission and the application uses the background location service, the user is presented with the *_Blue Bar of Shame_* (for more information check out [this blog post](https://blog.set.gl/ios-11-location-permissions-and-avoiding-the-blue-bar-of-shame-1cee6cd93bbe)):
* Added `useSignificantChanges` boolean to the options passed.
* Added `_usingSignificantChanges` boolean based on user options. If `true`, then the CLLocationManager will use functions `startMonitoringSignificantLocationChanges`/ `stopMonitoringSignificantLocationChanges` rather than the standard location services.
* Changed method signature of `beginLocationUpdatesWithDesiredAccuracy` to include `useSignificantChanges` flag
* Added check for new `NSLocationAlwaysAndWhenInUseUsageDescription`
All unit tests passed.
Tested in simulator and on device, toggling `useSignificantChanges` option when calling `watchPosition`. Results were as expected. **When `TRUE`, the _Blue Bar of Shame_ was not present.**
Changes do not affect Android and location services still work as expected on Android.
* Change is for iOS only
* Using a different API will have different accuracy results. Adding `useSignificantChanges` as an option was by design so apps that want to have most accurate and most frequent update can still use standard location services.
Closes https://github.com/facebook/react-native/pull/15062
Differential Revision: D5443331
Pulled By: javache
fbshipit-source-id: 0cf5b6cd831c5a7c8c25a5ddc2e410a9aa989bf4
f7043699b0
