Question

I’m trying to figure out how to reposition the MKMap region programmatically so that my annotation (automatically selected when the map loads) will all fit centered.

Current Result: https://www.evernote.com/shard/s46/sh/7c7d2ed8-203c-4878-af8c-83ff77ad7b21/ce7786acdf66b0782fc689b72d1b67e7

Desired Result: https://www.evernote.com/shard/s46/sh/21fb0eab-d5c4-4e6d-b05b-322e7dcce8ab/ab816f2a24f11b9c9e15bf55ac648f72

I have tried to reposition everything in - (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views but that didn’t work. Is there a better approach?

// here is viewWillAppear logic

[self.mapView removeAnnotations:self.mapView.annotations];

CLGeocoder *geocoder = [[CLGeocoder alloc] init];

CLGeocodeCompletionHandler completionHandler = ^(NSArray *placemarks, NSError *error) {

if (error) {

  EPBLog(@"error finding placemarks: %@", [error localizedDescription]);

} else {

  if (placemarks) {

    [placemarks enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

      CLPlacemark *placemark = (CLPlacemark *)obj;

      if ([placemark.country isEqualToString:@"United States"]) {

        EPBAnnotation *annotation = [EPBAnnotation annotationWithCoordinate:placemark.location.coordinate];

        annotation.title    = self.locationObj.locationName;
        annotation.subtitle = self.locationObj.locationAddress;

        [self.mapView addAnnotation:annotation];

        self.mapView.selectedAnnotations = @[annotation];

        [self.mapView setCenterCoordinate:placemark.location.coordinate];

        /**
         * @todo
         * MOVE THIS OUTTA HERE
         */

        MKCoordinateRegion region = {{0.0f, 0.0f}, {0.0f, 0.0f}};

        region.center = placemark.location.coordinate;

        region.span.longitudeDelta = 0.003f;
        region.span.latitudeDelta  = 0.003f;

        [self.mapView setRegion:region animated:YES];
        [self.mapView regionThatFits:region];

        *stop = YES;
      }
    }];
  }
}
};

[geocoder geocodeAddressString:self.locationObj.locationAddress completionHandler:completionHandler];

Answer 1

Following method will fit the map on region to show all annotations. You can call this method in Map’s didAddAnnotations method.

- (void)zoomToFitMapAnnotations { 

    if ([mMapView.annotations count] == 0) return;
    int i = 0;
    MKMapPoint points[[mMapView.annotations count]];

    //build array of annotation points
    for (id<MKAnnotation> annotation in [mMapView annotations]){
         points[i++] = MKMapPointForCoordinate(annotation.coordinate);
    }

    MKPolygon *poly = [MKPolygon polygonWithPoints:points count:i];
    [mMapView setRegion:MKCoordinateRegionForMapRect([poly boundingMapRect]) animated:YES]; 
}

Howevcer you should see if you want to add user location annotation in visible area also. If you don’t then in loop check if current annotation is MkUserLocation and don’t add it’s points in points array.

if ([annotation isKindOfClass:[MKUserLocation class]]) {
    continue:
}

Now if you wanted an Annotation to be in center and selected automatically then do this

annotation.coordinate=mMapView.centerCoordinate;
[mMapView selectAnnotation:annotation animated:YES];