Revert to user location from map with better GPS accuracy

mobile/src/ui/Geolocation.js

@@ -15,36 +15,35 @@ export class Geolocation extends Component {
 
   constructor(props) {
     super(props)
-    reactAutoBind(this)
-
-    if (props.watch) {
-      this.intervalId = setInterval(this.updateLocation, config.geoSampleDelay)
-    } else {
-      this.intervalId = -1
-    }
+    this.watchId = -1
   }
 
   componentDidMount() {
-    this.updateLocation()
-  }
-
-  componentWillUnmount() {
-    if (this.intervalId !== -1) {
-      clearInterval(this.intervalId)
-      this.intervalId = -1
-    }
-  }
-
-  updateLocation() {
     navigator.geolocation.getCurrentPosition(
       (position) => {
         this.props.onUpdate(position)
+
+        if (this.props.watch) {
+          ;(this.watchId = navigator.geolocation.watchPosition((position) =>
+            this.props.onUpdate(position)
+          )),
+            null,
+            { distanceFilter: 5, maximumAge: 0, enableHighAccuracy: true }
+        }
       },
       null,
       { distanceFilter: 5, maximumAge: 0, enableHighAccuracy: true }
     )
   }
 
+  componentWillUnmount() {
+    if (this.watchId !== -1) {
+      navigator.geolocation.clearWatch(this.watchId)
+      navigator.geolocation.stopObserving()
+      this.watchId = -1
+    }
+  }
+
   render() {
     return null
   }