Expo Setup

npx expo install react-native-background-geolocation
npx expo install expo-gradle-ext-vars

:open_file_folder: app.json

• Add the following plugins:

{
  "expo": {
    "name": "your-app-name",
    "plugins": [
+     [
+       "react-native-background-geolocation", {
+         "license": "YOUR ANDROID LICENSE KEY"
+       }
+     ],
+     [
+       "expo-gradle-ext-vars", {
+         "googlePlayServicesLocationVersion": "21.1.0"
+       }
+     ]
    ]
  }
}

Polygon Geofencing Support

If you've purchased the Polygon Geofencing add-on for creating geofences of any shape, you can add the "Polygon Geofencing" entitlement to your existing Background Geolocation license key in the Customer Dashboard.

Info.plist: Usage Descriptions

• Add the following Usage Descriptions to the ios.infoPlist section:
• These strings are used by the OS when requesting permission from the user. It's up to you to re-write these strings as-desired.

{
  "expo": {
    "name": "your-app-name",
    .
    .
    .
    "ios": {
+     "infoPlist": {
+       "NSLocationAlwaysAndWhenInUseUsageDescription": "[CHANGEME] This app requires location in the background",
+       "NSLocationWhenInUseUsageDescription": "[CHANGEME] This app requires location while in use",
+       "NSMotionUsageDescription": "[CHANGEME] This app uses motion-detection to determine the motion-activity of the device (walking, vehicle, bicycle, etc)"
+     }
    }
  }
}

• If you configure the plugin with locationAuthorizationRequest: 'WhenInUse', you can omit NSLocationAlwaysAndWhenInUseUsageDescription
• If you configure the plugin with disableMotionActivityUpdates: true, you can omit NSMotionUsageDescription

Info.plist: UIBackgroundModes:

• Add the following UIBackgroundModes to the ios.infoPlist section:

{
  "expo": {
    "name": "your-app-name",
    .
    .
    .
    "ios": {
      "infoPlist": {
        "NSLocationAlwaysAndWhenInUseUsageDescription": "[CHANGEME] This app requires location in the background",
        "NSLocationWhenInUseUsageDescription": "[CHANGEME] This app requires location while in use",
        "NSMotionUsageDescription": "[CHANGEME] This app uses motion-detection to determine the motion-activity of the device (walking, vehicle, bicycle, etc)",
+       "UIBackgroundModes": [
+         "location",
+         "fetch",
+         "processing"
+       ],
+       "BGTaskSchedulerPermittedIdentifiers": [
+         "com.transistorsoft.fetch",
+         "com.transistorsoft.customtask"
+       ]
      }
    }
  }
}

• While field-testing the plugin configured with debug: true (to enable debug found FX), you can optionally add the UIBackgroundMode audio so you can hear debug sounds while your app is in the background:

{
  "expo": {
    "name": "your-app-name",
    .
    .
    .
    "ios": {
      "infoPlist": {
        "NSLocationAlwaysAndWhenInUseUsageDescription": "[CHANGEME] This app requires location in the background",
        "NSLocationWhenInUseUsageDescription": "[CHANGEME] This app requires location while in use",
        "NSMotionUsageDescription": "[CHANGEME] This app uses motion-detection to determine the motion-activity of the device (walking, vehicle, bicycle, etc)",
        "UIBackgroundModes": [
          "location",
          "fetch",
          "processing",
+         "audio"
        ]
      }
    }
  }
}

Info.plist: iOS License Key

• From the Customer Dashboard, add your iOS license key to your Info.plist:

{
  "expo": {
    "name": "your-app-name",
    .
    .
    .
    "ios": {
      "infoPlist": {
+       "TSLocationManagerLicense": "<YOUR IOS LICENSE KEY>"
      }
    }
  }
}

Re-build

You must rebuild your Android app for the added plugins to be evaluated.

• If you're developing locally:

npx expo prebuild

$ npx expo run:android
$ npx expo run:ios

• If you're using Expo EAS, you must first run eas build.
• Adjust --profile as desired.
• You must build ALL platforms, both iOS and Android:

 eas build --profile development

react-native-background-fetch

// Execute a task about every 15 minutes:
BackgroundFetch.configure({
  minimumFetchInterval: 15
}, async (taskId) => { // <-- This is your periodic-task callback  
  const location = await BackgroundGeolocation.getCurrentPosition({
    samples: 3,
    extras: {   // <-- your own arbitrary meta-data
      "event": "getCurrentPosition"
    }
  });
  console.log('[getCurrentPosition]', location);
  BackgroundFetch.finish(taskId);   // <-- signal that your task is complete
})