FBAnnotationClustering is an iOS library for clustering map notifications in an easy and performant way. Check out the blog post about it.

Create your clustering manager (and initialize with annotations or add annotations later):

self.clusteringManager = [[FBClusteringManager alloc] initWithAnnotations:arrayOfAnnotations];

Implement MKMapView delegate method mapView:regionDidChangeAnimated: to display annotations grouped in clusters on the map. An example of implementation:

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
    [[NSOperationQueue new] addOperationWithBlock:^{
        double scale = self.mapView.bounds.size.width / self.mapView.visibleMapRect.size.width;
        NSArray *annotations = [self.clusteringManager clusteredAnnotationsWithinMapRect:mapView.visibleMapRect withZoomScale:scale];
        
        [self.clusteringManager displayAnnotations:annotations onMapView:mapView];
    }];
}

Important: Call the method mapView:regionDidChangeAnimated: whenever you want to refresh currently visible map rectangle by yourself (for example, if you added annotations to clusteringManager)

All clusters will have FBAnnotationCluster class, so when MKMapView delegate methods are called, you can check if current annotation is cluster by checking its class. For example:

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{   
    if ([annotation isKindOfClass:[FBAnnotationCluster class]]) {
        FBAnnotationCluster *cluster = (FBAnnotationCluster *)annotation;
        NSLog(@"Annotation is cluster. Number of annotations in cluster: %lu", (unsigned long)cluster.annotations.count);
    } else {
		NSLog(@"Normal annotation.")
    }	
        
    ...
} 

To run the example project; clone the repo, and run pod install from the Example directory first.

• iOS SDK 6
• ARC

FBAnnotationClustering is available through CocoaPods, to install it simply add the following line to your Podfile:

pod "FBAnnotationClustering"

If you don't like Cocapods, you can add all files from FBAnnotationClustering directory to your project.

• replace NSRecursiveLock with GCD serial queue

• removeAnnotations: method

    /**
     Remove array of annotations from current annotation collection.
  
     @param annotations Custom annotation objects.
     */
    - (void)removeAnnotations:(NSArray *)annotations;
  

Filip Beć, [email protected]

Maintained by Infinum

FBAnnotationClustering is based on a blog post written by thoughtbot.

FBAnnotationClustering is available under the MIT license. See the LICENSE file for more info.