Updating MKannotation image without flashing - objective-c

Question

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?

Answer 1

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;

Answer 2

Swift version of Anna answer:
annotation.customImage = ... //the new image
let av = self.mapView.viewForAnnotation(dnwl!)
av?.image = annotation.customImage

Answer 3

It seems you are using your own custom views for the annotations, in that case you can simply add a "refresh" method to your custom view and call it after you have updated the underlying annotation (ie: a custom view -a derived class from MKAnnotationView- is always attached to a potentially custom "annotation" class that conforms to the MKAnnotation protocol)
*) CustomAnnotationView.h
#interface CustomAnnotationView : MKAnnotationView
{
...
}
...
//tell the view to re-read the annotation data it is attached to
- (void)refresh;
*) CustomAnnotationView.m
//override super class method
- (void)setAnnotation:(id <MKAnnotation>)annotation
{
[super setAnnotation:annotation];
...
[self refresh];
}
- (void)refresh
{
...
[self setNeedsDisplay]; //if necessary
}
*) Where you handle the MKMapView and its annotations
for(CustomAnnotation *annotation in [m_MapView annotations])
{
CustomAnnotationView *annotationView = [m_MapView viewForAnnotation:annotation];
[annotationView refresh];
}