Force MKMapView viewForAnnotation to update

Question

So I have a MKMapView with all my pins added, and the colour of the pin is dependent on whether a value is set for that pin. When I first load the app, viewForAnnotation

Answer 1

Swift 2.1:

I had the same issue, and found a quick solution, trigger this when needed, also sending it to the main thread would be wise:

var annotationsArray = mapView.annotations
mapView.removeAnnotations(mapView.annotations)
mapView.addAnnotations(arrayIncs)
arrayIncs.removeAll()

Answer 2

Due to the way the map view caches its annotations, you NEED to remove and re-add the annotation if you need to make changes to its appearance. A simple remove & add is the way to go. There is no cache invalidating mechanism but this.

Answer 3

Actually, I dont' know if this worked for you but this is how I did it.

I didn't need to delete the annotation from map. All I need to do is tell the map to give me the annotation view for a parameter annotation. The map will return the correct annotation. From there, I have a property for my custom annotation to identify whether it is an active item, if yes, show the normal pin image, else show full pin image.

-(void)updateAnnotationImage:(CustomAnnotation *)paramAnnotation
{
    MKAnnotationView *av = [geoMap viewForAnnotation:paramAnnotation];

    if (paramAnnotation.active)
    {
        av.image = [UIImage imageNamed:@"PinNormal.png"];
    }
    else
    {
        av.image = [UIImage imageNamed:@"PinFull.png"];
    }
}

Bit late but hopefully it helps others who came across this problem.

Answer 4

I also found this answer helpful: In which case that mapView:viewForAnnotation: will be called?

Whenever you call addAnnotation method

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id < MKAnnotation >)annotation gets called. 

Answer 5

Just spent a couple of hours to get this to work on Xamarin; this is a warning for other Xamarin developers. Make sure you use the ViewForAnnotation method and not the GetViewForAnnotation delegate. I was using the wrong method which returned new annotation views instead of the existing ones... of course it wasn't working!