MapKit and asynchronous network calls to the foursquare API
Note: To actually run the app, you need to get your API token from the Foursquare API! It's really easy. Go to https://developer.foursquare.com, log in, and find your oauth_token and you should be good to go! Just make sure you fill it in at the top of PlacesMapViewController (there should be a warning there).