Changed method signatures of uploadGPXTraining and initWithGPX to pass NSData, so any GPX data will be parsed within the Dailymile library
Added some DMErrorCode constants and handled error, if the GPX track is ever nil in DailymileActivity
Made progress with uploading an entry to dailymile without GPX. But uploadGPXTraining is left incomplete and in a mess for now, until I can find priority to work on GPX again
Added an enumerated type DailymileDistanceUnit for the distanceUnit property; Created some static test data from the calling view controller, to use for as an alternative to the GPX data
Created some custom getters in DailymileActivity for the purpose of error handling, to return empty strings instead of nil. Cleans up parameters set in DailymileManager