Regarding iPhone Map Kit cluster pinpoints:
I have 1000\'s of marks that I want to show on the map but it\'s just too many to handle so I want to cluster them.
I recently had to implement annotation clustering with MapKit. The solutions mentioned above are good, depending on your use case. I ended up going with FBAnnotationClustering (Objective-C) because it was free, and had lots of stars and few issues on github:
https://github.com/infinum/FBAnnotationClustering
The app I was working on was very map-centric, so it made sense to translate FBAnnotationClustering into Swift. Here's a blog post on the approach, which includes a link to the sample project on github.
http://ribl.co/blog/2015/05/28/map-clustering-with-swift-how-we-implemented-it-into-the-ribl-ios-app/