Open a pdf on iOS (iPad)

I’m a long ago user of NSBasic, having developed multiple commercial apps for PalmOS (I did say “long ago”…).

Right now, I’ve got one of my staff working to develop an app that will solicit a filename (via an input box), verify that the file exists, and then open it for viewing in the device’s default pdf viewer. The target device is iPad with iOS.

Can someone point him/me in the right direction? Given the name and location of an existing file, how does one cause that file to pop open?

Here’s a similar thread that is also active now: