I have a quick question, does the core location in iOS 4.3.2 automatically use assisted gps or is this an option you need to choose.
I am working with the GPS and I
It's all automatic. The best you can do is check the altitude, which is undefined when a GPS fix is not available yet.
edit: see http://developer.apple.com/library/mac/#documentation/CoreLocation/Reference/CLLocation_Class/CLLocation/CLLocation.html
if verticalAccuracy < 0, altitude is invalid (from which you can infer no GPS fix)