As stated on their site:
MyNudeWorld for i-Phone
We have created one of the world’s easiest to use App which will enable you to find all the nudist and naturist events , parties , meet-up groups , beaches , groups, organizations and destinations anywhere in the world at a click of a button.
The iPhone app is available here. Since the development of the iPhone app, an Android app has also become available, which you can find on the Google Play-store here. Unfortunately the reviews on both sides are not very flattering, but they’re quite dated. Too bad, since either version of the app will cost you $6.99.
Perhaps the program has been updated, so use at own risk!
Another app for the iphone is iSwimNu.de, an app that will help you find places to swim in the nude all over the world.