Instead, to Identify users I do the following instead.
Create an implementation of CrashManagerListener, which overrides UserID, Contact and Description.
Then use it as follows when registering the CrashManager
On iOS you need to implement BITHockeyManagerDelegate where you need to override UserIdForHockeyManager(), UserNameForHockeyManager() and UserEmailForHockeyManager().
Then right before starting the SharedHockeyManager you need to register your Delegate.
Now the User and Contact columns in a crash report on HockeyApp should be filled out with the values you provided.