Multiple annotations (iOS) The easiest way

Question

I use annotations in IOS to display stations on the London tube, but I look at the numbers and there are about 280. The easiest way to do this? Individually or is there another option?

Cheers for all the tips.

David

Answer 1

Performance is good with 280 annotations; appearance is not. You must group them in clusters when the user is scaled.

One way to do this:

• Determine how many cluster annotations you want to show.
• Divide the screen into x * y tiles by approximately x*y =~ numClusters and x/y=480/320=1.5 x*y =~ numClusters x/y=480/320=1.5
• Add a cluster annotation to each fragment (this is a regular cluster with an array containing 0 or more annotations).
• Run k-mean algorithm :
  • Iterate over all annotations and add them to the nearest cluster.
  • Calculate a new center for each cluster, which will be the average center of all its members.
  • Clear each cluster.
  • Repeat until the cluster moves more.
  • Delete empty clusters, if any.

You fall into numClusters clusters arranged according to the density of annotation.

You can also leave a series of regular annotations yourself if they are outside the clusters. Depends on how you want it to look.