Most Useful services/methods for Geocoding in Augmented Reality app for iPhone?

I'm building an Augmented Reality application in the fashion of Yelp, and need to access the geodata of various buildings in as accurate a fashion as possible. What is the most accurate Geocoding service available? 开发者_运维百科Price is also an factor, but less so than the accuracy of the data.

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From my experiences, Google's geocoding service is incredibly precise, especially when using address data that is missing information or is formatted incorrectly. Though google does limit you to how many geocode requests you can have per day.

WebGIS is (currently) an unlimited geocoding web service, though it is a little harder to get precise results with malformed address data.