How to check if anyone is enter/left in/from particular boundary area even if application is in background mode or kill mode?

Question

I want to check if anyone enter in allocated boundary then i have to alert that user like "You are entered" and when user leaves then "You left". I am using .KML file for draw boundary in which there are more than latitude and longitude. Here i attached screenshot for the same.So, my concern is that how can i detect that anyone is entered within this boundary and left from that boundary. Thank you in advance Boundary looks like this.Red color line is boundary.

Answer 1

Use map rects. Here's an example using the map's current visible rect. With regards to your question, you could use convertRegion:toRectToView: to first convert your region to a MKMapRect beforehand.

MKMapPoint userPoint = MKMapPointForCoordinate(mapView.userLocation.location.coordinate);
MKMapRect mapRect = mapView.visibleMapRect; // find visible map rect
//MKMapRect mapRect = [self getMapRectUsingAnnotations:arrCordinate];//find custom map rect
BOOL inside = MKMapRectContainsPoint(mapRect, userPoint);

MKMapRect mapRect = mapView.visibleMapRect; Create your custom mapRect using your boundary region from multiple latitude and longitude

- (MKMapRect) getMapRectUsingAnnotations:(NSArray*)arrCordinate {

    MKMapPoint points[[arrCordinate count]];

    for (int i = 0; i < [arrCordinate count]; i++) {
        points[i] = MKMapPointForCoordinate([arrCordinate[i] MKCoordinateValue]);
    }

    MKPolygon *poly = [MKPolygon polygonWithPoints:points count:[arrCordinate count]];

    return [poly boundingMapRect];
}

Answer 2

Try this code. This is based on Winding Number Algorithm. This works for complex shapes such as your red line.

typedef struct {
  double lon;
  double lat;
} LATLON;

// returns true if w/in region
bool chkInRegion(LATLON poi, int npoi, LATLON *latlon)
{
  int wn = 0;
  for (int i = 0 ; i < npoi-1 ; i++) {
    if (latlon[i].lat <= poi.lat && latlon[i+1].lat > poi.lat) {
      double vt = (poi.lat - latlon[i].lat)/(latlon[i+1].lat - latlon[i].lat);
      if (poi.lon < (latlon[i].lon + (vt * (latlon[i+1].lon - latlon[i].lon)))) {
        wn++;
      }
    } else if (latlon[i].lat > poi.lat && latlon[i+1].lat <= poi.lat) {
      double vt = (poi.lat - latlon[i].lat)/(latlon[i+1].lat - latlon[i].lat);
      if (poi.lon < (latlon[i].lon + (vt * (latlon[i+1].lon - latlon[i].lon)))) {
        wn--;
      }
    }
  }
  return wn < 0;
}

// test data
LATLON llval[] = {
  {100,100},
  {200,500},
  {600,500},
  {700,100},
  {400,300},
  {100,100}
};
#define NLATLON (sizeof(llval)/sizeof(LATLON))

int main(int argc, char **argv) {
  while (1) {
    char buf[1024];
    fprintf(stderr, "lon = ");
    fgets(buf, sizeof(buf), stdin);
    double lon = atof(buf);
    fprintf(stderr, "lat = ");
    fgets(buf, sizeof(buf), stdin);
    double lat = atof(buf);
    LATLON ltest;
    ltest.lat = lat;
    ltest.lon = lon;
    if (chkInRegion(ltest, NLATLON, llval)) {
      fprintf(stderr, "\n*** in region ***\n\n");
    } else {
      fprintf(stderr, "\n=== outside ===\n\n");
    }
  }
  return 0;
}

Answer 3

Geofencing will not work on complex polygon shaped regions. May be you can solve the problem with some other approach. For instance divide the region into smaller CLCircularRegion and then develop aggregate logic for the case where you have to show notification for all those locationManager:didEnterRegion: and locationManager:didExitRegion: callbacks. But keep in mind that only a max of 20 simultaneous monitored regions per app are allowed.

Refer https://forums.developer.apple.com/thread/21323 phillippk1 suggestion for other possible approach.