Superpin will call mapView:viewForAnnotation: delegate method for all annotations it’s about to show, including clusters. If your delegate responds, the returned view will be shown. That’s one way to customize cluster appearance.

If your delegate doesn’t respond (or returns nil), Superpin will use builtin SPClusterView class to render clusters.

If you’d like to avoid subclassing or writing your own custom class, you can use following methods on SPClusterView to tweak it’s look:

+[SPClusterView setBackgroundImage:(UIImage*)image]
+[SPClusterView setTextColor:(UIColor)color]
+[SPClusterView setFont:(UIFont*)font]
+[SPClusterView setEdgeInsets:(UIEdgeInsets)edgeInsets]

For example, if you’d like to show black transparent clusters in Aiports sample:

Airports sample with customized cluster appearance

you could just use something like this:

[SPClusterView setBackgroundImage:[UIImage imageNamed:@"cluster_black.png"]]; 
[SPClusterView setTextColor:[UIColor whiteColor]];