Generally you don’t need to provide a subclassed dealloc method as ARC manages the lifetime of the instance variables.
However it can be useful to perform clean-up other than releasing objects, for example to remove an observer or close a network connection down cleanly. You are therefore allowed to subclass dealloc under ARC, but you are not allowed to call [super dealloc] from within the subclassed method.
In your particular case it’s not required, however.