For an iPad, or iPod touch, is there a way to find out if the device has GPS?
Extra Credit: What if the iPad itself does not, but it is connected to a third-party GPS unit? Can I determine this?
For iOS 6 or higher, you might want to try
+ (BOOL)[CLLocationManager deferredLocationUpdatesAvailable]
According to the documentation:
Deferred location updates require the presence of GPS hardware and may not be supported on all iOS devices.