The Inspector Alert Radiation App from International Medcom pairs with iPhones and iPads. This powerful app:

-Logs radiation levels along with time, date and GPS coordinates
-Displays current and recent radiation levels
-Allows data sharing by email or twitter
-Allows automatic sharing of data with Safecast or your own network
-Pairs with Apple Watch for viewing radiation levels and notifications on your wrist
-Creates a kml file that can import directly into Google Earth for viewing