I\'ve listed here Yahoo Integration steps which I\'ve followed.
fetchProfileWithDelegate: (source here) builds a URL and sets some header info, then passes this data to [YOSRequestClient -sendAsyncRequestWithDelegate:] (source here).
The request client then creates a NSMutableURLRequest and NSURLConnection and starts a connection.
Once the data is downloaded (if any) YOSResponseData takes over and creates a new object from the downloaded data (source code here).
There is no code path I can see that would allow the serviceResponseData object passed in to be nil. You should at least be able to see [data didSucceed], which will tell you if the HTTP response was < 400. Oddly enough, if the server just opens and closes the connection with no HTTP response, I believe [data didSucceed] == YES even though it obviously didn't succeed (since 0 < 400).
It doesn't look like you're doing anything wrong. My guess is that since the last commit was 4 years ago, and the company has gone through significant restructuring since then, the project has been abandoned and nobody has bothered making a note of it.
Update: In addition to having no updates for 4 years, Yahoo's developer forum for this software has been closed. I don't think Yahoo's API for this software is working any more. –