hasLocationPermission = () => {
try{
  const granted = PermissionsAndroid.request(
    PermissionsAndroid.PERMISSIONS.ACCESS_FINE_LOCATION,
    {
      title: 'Location Permission',
      message: 'You must to accept this to make it work.'
    }
  )
  if(granted === PermissionsAndroid.RESULTS.GRANTED){
    console.log('Location permission accepted.')
  }else{
    console.log("Location permission denied")
  }
} catch (err) {
  console.warn(err)
}
}

getUserLocationHandler = () => {
if(this.hasLocationPermission){
  Geolocation.getCurrentPosition(
    position => {
      this.setState({
        userLocation: {
          latitude: position.coords.latitude,
          longitude: position.coords.longitude,
          latitudeDelta: 0.0622,
          longitudeDelta: 0.0421,
        },
      });
    },
    err => console.log(err),
    {
      enableHighAccuracy: true,
      timeout: 15000,
      maximumAge: 10000

    }
  );
}
}

 render() {
return (
  <View style={styles.container}>
    <FetchLocation onGetLocation={this.getUserLocationHandler}/>
    <UsersMap userLocation={this.state.userLocation}/>
  </View>
);
}

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />