Zoom mapview to a region where pins are dropped - iphone

Question

If I have 3 pins in a mapview, how will I zoom to these pins, when the map loads. That is, when the map loads I need to have a zoomed view, but the view should accomodate all pins dropped in the map. Its working, when the map has just one pin. But I cant handle zoom with multiple pins. Help needed

Answer 1

The below method will do that,
- (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(MapAnnotation *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) * 1.1;
// Add a little extra space on the sides
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1;
// Add a little extra space on the sides
region = [mapView regionThatFits:region];
[mapView setRegion:region animated:YES];
}

Answer 2

I wrote the below code in an App and it is similar to #ElanthiraiyanS Answer
-(void)zoomToFitMapAnnotations:(MKMapView*)mapView insideArray:(NSArray*)anAnnotationArray
{
// NSLog(#"%s", __FUNCTION__);
if([mapView.annotations count] == 0) return;
CLLocationCoordinate2D topLeftCoord;
topLeftCoord.latitude = -90;
topLeftCoord.longitude = 180;
CLLocationCoordinate2D bottomRightCoord;
bottomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;
for(MKPointAnnotation* annotation in anAnnotationArray)
{
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) * 1.1; // Add a little extra space on the sides
region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1; // Add a little extra space on the sides
region = [mapView regionThatFits:region];
[mapView setRegion:region animated:YES];
}

Answer 3

you may calc the center of all pins
- (CLLocationCoordinate2D)centerPointFromAnnotationArray:(NSArray *)array
{
CLLocationCoordinate2D coorMax = CLLocationCoordinate2DMake(0, 0);
CLLocationCoordinate2D coorMin = CLLocationCoordinate2DMake(999, 999);
for ( int i = 0 ; i < [array count] ; ++i )
{
LMPoint *a = [array objectAtIndex:i];
if ( ( a.coordinate.latitude != 0.0f ) || ( a.coordinate.longitude != 0.0f ) )
{
if ( a.coordinate.latitude > coorMax.latitude )
{
coorMax.latitude = a.coordinate.latitude;
}
if ( a.coordinate.longitude > coorMax.longitude )
{
coorMax.longitude = a.coordinate.longitude;
}
if ( a.coordinate.latitude < coorMin.latitude )
{
coorMin.latitude = a.coordinate.latitude;
}
if ( a.coordinate.longitude < coorMin.longitude )
{
coorMin.longitude = a.coordinate.longitude;
}
}
}
CLLocationCoordinate2D coorCenter = CLLocationCoordinate2DMake((coorMax.latitude+coorMin.latitude)/2, (coorMax.longitude+coorMin.longitude)/2);
return coorCenter;
}
then zoom at the point with a proper zoomlevel