Multiple Annotations (IOS) Easiest way

Im using Annotations in IOS to display London Tube stations, but im looking at numbers and there are 280开发者_开发百科 or so. Whats the easiest way to do this? Individually or is there another option?

Cheers for all the advice

David

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The performance is good with 280 annotations, the appearance is not. You have to group them into clusters when the user zooms out.

One way to do it is:

• Decide how many cluster annotations you want to show.
• Split the screen in x*y tiles so roughly x*y =~ numClusters and x/y=480/320=1.5
• Add a cluster annotation per tile (it's a normal cluster with an array containing 0 or more annotations).
• Run the k-means algorithm:
  • Iterate all annotations and add each one to the closest cluster.
  • Calculate a new center for each cluster, which will be an average of the centers of all its members.
  • Empty each cluster.
  • Repeat until no cluster moves any longer.
  • Remove empty clusters, if any.

You end up with numClusters clusters positioned according to the annotation density.

You can also leave a number of normal annotations on their own if they are away from the clusters. Depends on how you want it to look.