Using UIButtonTypeInfoLight throws exception

Question

One of the iPhone code samples from Apple is the BubbleLevel app. On trying to build the project, the line below throws an exception which reads "error: 'UIButtonTypeInfoLight' undeclared (first use in this function)". Changing UIButtonTypeInfoLight to some other valid value will allow the project to build, but I can't tell if the simulator is actually running it correctly (the level appears and then is gone after 2-3 secs). At this point I'm only using the Simulator to try out some of the samples, but can't find any references on how one would use UIButtonTypeInfoLight properly. What reference would show how to call this properly?

UIButton *infoButton = [[UIButton buttonWithType:UIButtonTypeInfoLight] retain];