反应本机 expo iOS 无法询问物理设备上的后台位置

Question

I am trying to get background permissions using expo Location. This works on android and on an iOS simulator but not on a physical iOS device.

const askLoc = async () => {
    const requestForeground = await Location.requestForegroundPermissionsAsync();
    if (requestForeground.status === 'granted') {
      const requestBackground = await Location.requestBackgroundPermissionsAsync();
      if (requestBackground.status === 'granted') {
        console.log('background location granted');
      }
    }
  };

This is what my app.json looks like.

"ios": {
      "infoPlist": {
        "NSCameraUsageDescription": "This app uses the camera to send pictures or create a new profile photo.",
        "NSPhotoLibraryAddUsageDescription": "User can download documents that were previously uploaded by company",
        "NSPhotoLibraryUsageDescription": "User can upload Photos/Documents to be seen by his/her company",
        "NSLocationAlwaysUsageDescription": "Location is shared with users company while he/she is completing a task/job.",
        "NSLocationWhenInUseUsageDescription": "Location is shared with users company while he/she is completing a task/job.",
        "NSUserActivityTypes": ["INSendMessageIntent", "INStartCallIntent"],
        "UIBackgroundModes": ["location", "fetch"],
        "CFBundleAllowMixedLocalizations": true
      }
    },

Answer 1

There are some factors you need to consider to debug the issue:

1. Make sure that location access enables. await Location.hasServicesEnabledAsync()

2. There's a probability that, recently, you deny location permission definitively. requestForeground.status will always resolve as denied

Detect if requestForeground.canAskAgain set to true otherwise user has already denied this permission and you can open device setting and user grant that permission manually.

Here permission response type definition

export interface PermissionResponse {
  status: PermissionStatus;
  expires: PermissionExpiration;
  granted: boolean;
  canAskAgain: boolean;
}