PlaceTagger is the best and easiest to use geotagging software for iPhone. Its simple 1-touch interface makes recording location data for photo shoots easier than any other solution on the market today. PlaceTagger is an end to end solution. It comes with a simple step-by-step guide to help you get started.
PlaceTagger works by recording location data periodically in a care free manner and offers options to increase accuracy or reduce battery usage. When you are done taking pictures, just connect to the same WiFi network with your iPhone and Leopard-based Mac and let PlaceTagger do the rest.