UIView 'falling rain' transparent overlay that can be clicked through?

I'd like to create a UIView which will animate falling rain, which should be above all other views, at the very front, but transparent, and it shouldn't register taps or interaction at all, so tapping the UI behind it should behave exactly as it does now, before I've implemented it. It'd act as an overlay, and nothing more.

Is this as simple as setting UserInteractionEnabled to NO, or is there more to it? Do I need to subclass UIView, or override something, etc.?