Open Radar

 
When many MKAnnotations are added to an MKMapView they can appear to be overlapping each other and the map can easily become unreadable.
There are tips and tricks to cluster/de-cluster you MKAnnotations based on current zoom level but they suffer from the following:
1. it's a lot of error-prone code to write, usually involving assigning your MKAnnotations (or the underlying data) to a quad-tree and performing quad-tree search on the fly base on zoom level.
2. even with a good quad-tree the visual treatment is usually very disappointing: the annotations appear clustered at one zoom level and suddenly jump when they de-cluster at a lower zoom level (and vice versa when clustering). Such jumps are the result of adding and removing MKAnnotations from the map: the link is lost between clusters and their content.