MKMapView在地图上加载成千上万的针脚

Question

I need to displays thousands of pins on the MKMapView and I need a good delegate method where I can add the pins. didUserUpdateLocation is bad because it is fired multiple times. What is the best way to add thousands of pins to the MKMapView.

UPDATE:

I just used a BOOL check to load the pins one time only and it seemed to work really good!

-(void) mapView:(MKMapView *) mv didUpdateUserLocation:(MKUserLocation *)userLocation
{
    NSLog(@"didUpdateUserLocation");

    if(self.isMapped) return; 

    for(Facility *facility in self.facilities) 
    {
        CLLocationCoordinate2D facilityCoord = { facility.latitude,facility.longitude };


        MapPoint *mp = [[MapPoint alloc] initWithCoordinate:facilityCoord title:facility.facilityName];



        [mv addAnnotation:mp];

    }

    self.isMapped = YES; 

}

Answer 1

I use mapView:regionDidChangeAnimated:. I pull data from Core Data filtering by latitude and longitude to get pins for the current region and surroundings so the user can scroll a bit without pulling data again.

When zooming out you can decide to show a clustered version of your data that you can precalculate or calculate at runtime using the K-Means algorithm.

It may help if you have a high amount of data to use a light data structure based on structs instead objects.

When adding and removing pins you may want to animate a fade-in/fade-out to smooth the transitions. It's a bad user experience to be popping in and out stuff on screen.

If server calls are involved in all this, you can encapsulate the calls in NSOperations so you can cancell old calls when the user moves too fast through the map.