I have a map view with a large quantity of annotations (3000+), when the user is zoomed to a reasonable level all is well and fast.

Although when the user zooms out and a large quanitiy of annotations come into view there is a lot of slow down due to the sheer amount of annotations being shown at once. What is the best way to handle this?

The current solution i am using:

- (void)mapView:(MKMapView *)_mapView regionDidChangeAnimated:(BOOL)animated {

    NSArray *annotations = [_mapView annotations];  
    MapAnnotation *annotation = nil; 

    for (int i=0; i<[annotations count]; i++)
    {
        annotation = (MapAnnotation*)[annotations objectAtIndex:i];
        if (_mapView.region.span.latitudeDelta > .010)
        {
            [[_mapView viewForAnnotation:annotation] setHidden:YES];
            warningLabel.hidden = NO;
        }
        else {
            [[_mapView viewForAnnotation:annotation] setHidden:NO];
            warningLabel.hidden = YES;
        }
    }
}

Works great although due to the sheer size of the loop this causes a lot of slow down when zooming in and out and scrolling around. I can't seem to think of a better way to handle this, is there a way to only loop through the annotations currently being displayed or something along those lines to reduce the size of the loop?

iphone objective-c mkmapview
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