Detect GPS hardware in iDevice?

You can add the gps key to your app's UIRequiredDeviceCapabilities array/dictionary in your app's plist. That will make the app require the GPS. Finding out if the device has a GPS at runtime is harder. I'll have to do some digging for that.

 

A slightly less "dodgy" way would be to check the vertical accuracy reading on location updates. If it is -1 (invalid) then the reading did not come from a GPS. You only get vertical location data from an actual GPS.

 

You may want to include a toggle or some other override method for those who have hardware like the iPad wifi, but use a 30 pin or bluetooth GPS (Dual xgps150, bad elf gps, Garmin GLO) for example.

 

But the location manager won't work with an external GPS, will it?

 

All I know is that you have to use either a 30 pin or bluetooth receiver made for iOS devices. Once hooked up, it is just like using the native GPS on those devices that have it, and it adds GPS to those devices that don't have them. The GPS works with all apps, the apps don't know that an external GPS position is being used vs the internal system.

Links to some of the units:

http://bad-elf.com/products/be-gps-1000/
http://xgps150.dualav.com
https://buy.garmin.com/shop/shop.do?pID=109827
http://www.gns-gmbh.com/index.php?id=194&L=1

 

The external GPS units have WAAS to increase the accuracy, and work places that the internal units gps does not, such as a jet aircraft in flight above 18,000' (which is why I have one.)

My understanding is that they are also popular with boaters.

Only downside it that an external unit doesn't use the cell network to help with the initial position fix, so the initial position can take slightly longer than the built in GPS.

 

Really? That's very odd. Which specific device, (e.g. second generation WiFi only iPad) and what OS version & subversion?