Difference between release and dealloc in objective-c

Question

When deallocing a refrence I\'ve seen release and dealloc being used for example

-(void)dealloc
{
  [foo release];
  [nar dealloc];         


        

Answer 1

Never call dealloc except as [super dealloc] at the end of your class's dealloc method. The release method relinquishes ownership of an object. When a Cocoa object no longer has any owners, it may be deallocated — in which case it will automatically be sent a dealloc message.

If you're going to program Cocoa, you need to read the Memory Management Guidelines. It's incredibly simple once you get over the initial hump, and if you don't understand what's in that document, you'll have lots of subtle bugs.

Answer 2

You're never supposed to call dealloc explicitly (unless it's [super dealloc] within the dealloc method, but that's the only exception). Objective-C handles memory management via reference counting, so you're simply supposed to match your allocs/retains with releases/autoreleases and let the object deconstruct itself.

Answer 3

The dealloc statement in your example is called when the object's retain count becomes zero (through an object sending it a release message).

As it is no longer needed, it cleans itself up by sending a release message to the objects that it is holding on to.