The Nike+ iOS SDK by Nike allows to communicate with the API interface to implement fitness monitoring features into applications. It contains XCode configuration and OAuth 2.0 authentication. Contact Nike to access full documentation as a partner.
Some developers don't just love code that runs--they also like to get out and run, themselves. And, because they're developers, they love to collect statistics and track their progress over time. If you're one of those people, good news: online service MyFitnessPal has provided the MyFitnessPal API to help its users bring together all their data from various devices and apps in a single place.