pasco is a cordova app. The logic is largely in javascript with some custom work built for iOS.
To get you up and running this should get you to the point where you can work on the normal web version:
For the iOS version you will need to be on a mac with XCode. Here are the commands to get going with this:
You should find the xcode project in cordova\platforms\ios\pasco.xcodeproj
i.e. what goes where.