The TempImageView itself has no outlets or actions, but the controller object TempController needs to communicate with it to tell it when the temperature value changes. One additional outlet in TempController is needed for this purpose.
You can always add an action or outlet to an existing custom class. Just make sure the header and implementation files of the class (if created) reflect the new outlet or action.
Before you move on the next step, be sure to collapse the listing of outlets and actions by clicking another class.
You've already created an instance of TempController; all you need to do now is connect it to the TempImageView instance through the tempImage outlet.