When should you call dealloc method? Is it possible to implement dealloc in ARC?

You can dealloc for memory management. Once an object “retainCount” reaches 0, a dealloc message is sent to that object. Never call dealloc on objects unless you call [super dealloc]; around the close of a overridden dealloc.
(void)dealloc
{
   [ivar release]; //Release any retained variables before super dealloc
   [super dealloc]; //Only place in your code you should ever call dealloc
}