iOS: Cannot request location always if we already have location when in use permission

[tallpants]

Bug report

If we have location when in use permission, requesting location always permission always returns denied, probably because of this line: https://github.com/react-native-community/react-native-permissions/blob/4017cbf0861b562bb48888f76cfa7c9a62c68ffc/ios/LocationAlways/RNPermissionHandlerLocationAlways.m#L38

Apple's documentation is pretty clear about how you're allowed to call requestAlwaysAuthorization if the current authorization status is either kCLAuthorizationStatusNotDetermined or kCLAuthorizationStatusAuthorizedWhenInUse. Calling this when we already have when-in-use authorization will prompt the user to upgrade to "always allow" location permissions.

But in the library we're assuming that if we currently have when-in-use authorization, we're not allowed to ask for always authorization.

I tested by manually calling requestAlwaysAuthorization in Objective-C after getting when-in-use authorization from react-native-permissions -- and the upgrade prompt shows up just fine.

This should be an easy fix (as far as I can tell).

Documentation for requestAlwaysAuthorization that explains this: https://developer.apple.com/documentation/corelocation/cllocationmanager/1620551-requestalwaysauthorization?changes=latest_minor&language=objc

[zoontek]

@tallpants This library already handle location permission escalation. The line you give is from the check method from RNPermissionHandlerLocationAlways.m, so there no issue here.

A normal permission escalation would be:

1. check that LOCATION_WHEN_IN_USE is granted and LOCATION_ALWAYS is denied.
2. request LOCATION_ALWAYS

[tallpants]

@zoontek doing request for LOCATION_ALWAYS will return RESULTS.BLOCKED right now if we have LOCATION_WHEN_IN_USE permission already.

[zoontek]

I just checked it, it's not that easy to fix it.

I explain myself: kCLAuthorizationStatusAuthorizedWhenInUse does not means that LOCATION_ALWAYS is requestable. It means that it might be requestable.
It's fixable, but will need a bit of work / test.

[tallpants]

You're right yea it's more complicated than I initially thought. Do you have any ideas on how to approach fixing it? My initial guess is that without some form of persistence (maybe to NSUserDefaults) about whether we've already requested LOCATION_ALWAYS once before in the app, it's not possible to reliably work with the existing API of check and request.

Something like this (pseudocode -- doesn't handle all the other cases):

- (void)checkWithResolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject {
  CLAuthorizationStatus authorizationStatus = [CLLocationManager authorizationStatus];
  BOOL hasRequestedLocationAlways = [NSUserDefaults standardDefaults] boolForKey:@"RNPermissionHandlerLocationAlways-hasRequested"];

  if (authorizationStatus == kCLAuthorizationStatusAuthorizedWhenInUse && hasRequestedLocationAlways) {
    return resolve(RNPermissionStatusDenied);
  } else {
    return resolve(RNPermissionStatusNotDetermined);
  }
}

... and similary setting the RNPermissionHandlerLocationAlways-hasRequested key in user defaults to true in the request method after calling requestAlwaysAuthorization (since it can only be called once).

Just an idea of course, maybe you can find a nicer way of solving.

[zoontek]

The core already has such helper method (https://github.com/react-native-community/react-native-permissions/blob/master/ios/RNPermissions.m#L324)

It might work, but we have to flag as requested only if the result isn't whenInUse.

[rolfb]

Would love the ability to call requestAlwaysAuthorization twice to get to Always faster too.

[mikehardy]

This is under discussion here as well: https://github.com/transistorsoft/react-native-background-geolocation-android/issues/938#issuecomment-668042805

By you @rolfb :-), just cross-linking here as you've got great research posted in the other issue

[rolfb]

Cheers, @mikehardy!

The other one is private though :-)

[mikehardy]

Ah true enough - it affects the public version, but either way may result in knowledge here :)

[rolfb]

It seems like you have to explicitly request WhenInUse first, then you can request Always directly after. If you request Always first and get While in use (as read from device settings) you can't request Always to trigger the "Change to always" alert and will have to wait for the system to trigger it. This is probably clear to most, just wanted to summarize.

[jdegger]

For reference, the background-geolocation-android private repo owner @christocracy posted this as a solution:

docs clearly state it must either be undetermined or when in use when requesting.

The code added to make this work is the || clause.

if ((status == kCLAuthorizationStatusNotDetermined) || ((lastStatus == kCLAuthorizationStatusAuthorizedWhenInUse) && ([desiredRequest isEqualToString:ALWAYS_STRING]) )) {
  .
  .
  .
}

I have tested by commenting-out the check for kCLAuthorizationStatusNotDetermined in this repo and this seems to work fine.

[tallpants]

@jdegger that'll work for the initial request -- but to keep the API consistent we also need to track manually when we've asked for it already and return DENIED -- because requestAlwaysAuthorization will just not do anything if it's called a second time.