MapView with display multiple Annotationpin in Dynamic Rect

-(void) locateAllLocationonMap {

    

    MKCoordinateRegion region;

MKCoordinateSpan span;

span.latitudeDelta=0.04;

span.longitudeDelta=0.04;

    

    region.span=span;  

// region.center = currentLocation; 

    [mapView removeAnnotations:[mapView annotations]];

    

    for (objBean in arrFilter) { ////arrFilter is array data

        

        CLLocationCoordinate2D location;

        location.latitude = [objBean.gps_lat doubleValue];

        location.longitude = [objBean.gps_long doubleValue];

        

        addAnnotationpins = [[AnnotationPins alloc] init];

        addAnnotationpins.objEvent = objBean;

        addAnnotationpins.title = objBean.title;

        addAnnotationpins.subtitle = [NSString stringWithFormat:@"%@ to %@",objBean.start_date,objBean.end_date];

        addAnnotationpins.coordinate = location;

        

        [mapView addAnnotation:addAnnotationpins];

        [arrAnnMapRect addObject:addAnnotationpins]; /// arrAnnMapRect is an blank array....

        region.center = location; 

        NSString *device = [[UIDevice currentDevice] model];

        

        if ([device isEqualToString:@"iPhone Simulator"]) {

            region.center = location;

        }

    }    

[mapView setRegion:region animated:TRUE];

[mapView regionThatFits:region];

    [self setMyMapRect];

}

-(void)setMyMapRect{

    MKMapRect flyTo = MKMapRectNull;

for (id <MKAnnotation> annotation in arrAnnMapRect) {

NSLog(@"fly to on");

        MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);

        MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 0);

        if (MKMapRectIsNull(flyTo)) {

            flyTo = pointRect;

        } else {

            flyTo = MKMapRectUnion(flyTo, pointRect);

        }

    }

    

    // Position the map so that all overlays and annotations are visible on screen.

    mapView.visibleMapRect = flyTo;

}