MKAnnotationView在收到事件时更新带有距离的标题和副标题

- (void)updateTitlesWithDistance {
    for (MKMapView *mapView in self.mapViews) {
        for (MKAnnotationView *annotationView in mapView.annotations) {
            if ([annotationView isKindOfClass:[MKPinAnnotationView class]]) {
                MKPinAnnotationView *pinAnnotationView = (MKPinAnnotationView *)annotationView;
                CLLocationDistance distance = [self distanceBetweenCurrentLocationAndPin:pinAnnotationView.coordinate];
                
                // Update title and subtitle with distance
                pinAnnotationView.title = [NSString stringWithFormat:@"%d meters away", (int)distance];
                pinAnnotationView.subtitle = [NSString stringWithFormat:@"Heading: %d", (int)(self.userLocation.heading * 100)];
            }
        }
    }
}

- (CLLocationDistance)distanceBetweenCurrentLocationAndPin:(CLLocationCoordinate2D)coordinate {
    CLLocation *userLocation = self.userLocation;
    CLLocationCoordinate2D currentCoordinate = self.mapView.centerCoordinate;
    
    return [userLocation distanceFromLocation:currentCoordinate];
}