SMCalloutView aims to be an exact replica of the private UICalloutView system control.
We all love those "bubbles" you get when clicking pins in MKMapView. But sadly, it's impossible to present this bubble-style "Callout" UI anywhere outside MKMapView. Phooey! So this class painstakingly recreates this handy control for your pleasure.
To use SMCalloutView in your own projects, simply copy the files SMCalloutView.h and SMCalloutView.m.
The comments in SMCalloutView.h do a lot of explaining on how to use the class, but the main function you'll need is presentCalloutFromRect:. You'll specify the view you'd like to add the callout to, as well as the rect defining the "target" that the popup should point at. The target rect should be in the coordinate system of the target view (just like the similarly-named UIPopover method). Most likely this will be target.frame if you're adding the callout view as a sibling of the target view, or it would be target.bounds if you're adding the callout view to the target itself.
You can study the included project's AppDelegate.m for a working example.
You can read more info if you wish in the blog post.
This class requires LLVM 4.0 with Automatic Reference Counting (ARC), enabled by default in modern Xcode projects.