Question

I use this tutorial for integrating MapKit to my application:
http://iphonebcit.wordpress.com/iphone-map-kit-tutorial/

CLLocationCoordinate2D coordinate;
coordinate.latitude = 49.2802;
coordinate.longitude = -123.1182;

NSUInteger count = 1;
for(int i = 0; i < 10; i++) {
    CGFloat latDelta = rand()*.035/RAND_MAX - .02;
    CGFloat longDelta = rand()*.03/RAND_MAX - .015;

    CLLocationCoordinate2D newCoord = {coordinate.latitude+latDelta, coordinate.longitude+longDelta};
    MapDemoAnnotation* annotation = [[MapDemoAnnotation alloc] initWithCoordinate:newCoord andID:count++];
    [mapView addAnnotation:annotation];
    [annotation release];
}

and

- (MKAnnotationView *)mapView:(MKMapView *)mapViewLocal viewForAnnotation:(id <MKAnnotation>)annotation {
MKPinAnnotationView *pinView = (MKPinAnnotationView*)[mapViewLocal dequeueReusableAnnotationViewWithIdentifier:@"Pin"];
if(pinView == nil) {
    pinView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"Pin"];
    pinView.pinColor = MKPinAnnotationColorPurple;
    pinView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
    pinView.animatesDrop = YES;
    pinView.canShowCallout = YES;
} else {
    pinView.annotation = annotation;
}
return pinView;

}

So the pins will set on the map randomly. In my application, the coordinates will change. How can I change the coordinates of the annotations, so they will be updated on the map?

Does anyone know?

Answer 1

At iPhone SDK 3.x you have to remove the pin annotations and set it again. That is not very nice if you have many annotations an your map.

I try to make it better so I ony display/renew my pin annotations which are on the screen. So if an user zoom in to New York, there won’t be pin annotations in San Francisco or other than the user can’t see. So the performance will be much better.

Perhaps in the future this would be possible. I hope so 🙂