How to reduce the zoom level of MKMapview with annotation? - iphone

Question

I'm having only one annotation in the mapview.
I'm using the following code to zoom to that annotation pin
- (void)zoomToFitMapAnnotations:(MKMapView *)mapView {
if ([mapView.annotations count] == 0) return;
CLLocationCoordinate2D topLeftCoord;
topLeftCoord.latitude = -90;
topLeftCoord.longitude = 180;
CLLocationCoordinate2D bottomRightCoord;
bottomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;
for(id<MKAnnotation> annotation in mapView.annotations) {
topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude);
bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude);
bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude);
}
MKCoordinateRegion region;
region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5;
region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;
region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 0.1;
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 0.1;
region = [mapView regionThatFits:region];
[mapView setRegion:region animated:YES];
}
But it zooms to the extreme, I need to reduce the zoom level so the user can see some area around the annotation.
I tried changing the values of region.span, but can't get the solution.
Any suggestions would be appreciated.

Answer 1

Are you sure that this code :
region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 0.1;
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 0.1;
doesn't return latitude/longitude = 0 ?
Try to hardcode the span to 0.05 or something close.
The code below will center your map to your current position , you can change locationManager.coordinates with your annotation.coordinates.
CLLocationManager *locationManager = [[CLLocationManager alloc] init];
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
MKCoordinateSpan span;
MKCoordinateRegion region;
span.latitudeDelta = 0.05;
span.longitudeDelta = 0.05;
location.latitude = locationManager.location.coordinate.latitude;
location.longitude = locationManager.location.coordinate.longitude;
NSLog(#"%f",location.latitude);
region.span = span;
region.center = location;
[_mapVIew setRegion:region animated:YES];

Answer 2

use this code to adjust your mapView zoom level
MKCoordinateRegion mapRegion;
// set the center of the map region to the now updated map view center
mapRegion.center = self.mapView.centerCoordinate;
mapRegion.span.latitudeDelta = 0.1;
mapRegion.span.longitudeDelta = 0.1;
mapView.region=mapRegion;

Answer 3

I used the below code for zooming to the annotation,
CLLocation *location = [[CLLocation alloc] initWithLatitude:[#"My annotation's latitude" doubleValue] longitude:[#"My annotation's longitude" doubleValue]];
MKCoordinateRegion mkr;
mkr.center = location.coordinate;
MKCoordinateSpan span;
span.latitudeDelta = 0.0144927536;
span.longitudeDelta = 0.0144927536;
mkr.span = span;
[mapView setRegion:mkr animated:YES];
Currently, it zooms to one mile around the lat long. If I want to zoom more or less, I'll change the latlong delta value.
ie, for 2 miles = 0.0144927536*2 and for 0.5 mile = 0.0144927536/2. I hope, it will be useful for others.