Q:

Updating MKannotation image without flashing

I want to update the images of some of my annotations on a mapview every 5 seconds, however I dont' want to remove and re-add them to the map as this causes them to 'flash' or refresh, (ie disapear then reappear). I want it to be seamless.
I've tried the following: 
//get the current icon
        UserAnnotation *annotation = [self GetUserIconWithDeviceId:deviceId];

        //make a new annotation for it 
        UserAnnotation *newAnnotation = [[UserAnnotation alloc]
                                         initWithCoordinate: userCoordinates
                                         addressDictionary:nil];
        newAnnotation.title = name;
        newAnnotation.userDeviceId = deviceId;
        NSInteger ageIndicator = [[userLocation objectForKey: @"ageIndicator"] integerValue];
        newAnnotation.customImage = [UserIconHelpers imageWithAgeBorder:ageIndicator FromImage: userImage];

        //if its not there, add it 
        if (annotation != nil){
            //move it 

            //update location
            annotation.coordinate = userCoordinates;

            //add new one 
            [self.mapView addAnnotation: newAnnotation];

            //delete old one 
            [self.mapView removeAnnotation: annotation];

        } else {
        //just addd the new one 
            [self.mapView addAnnotation: newAnnotation]; 
        }

as a thought that if I added the new icon on top I could then remove the old icon, but this still caused the flashing. 
Has anyone got any ideas? 

A:

In the case where the annotation is not nil, instead of adding and removing, try this:
annotation.customImage = ... //the new image
MKAnnotationView *av = [self.mapView viewForAnnotation:annotation];
av.image = annotation.customImage;

