Vincent Gable’s Blog

May 19, 2010


Filed under: Cocoa,iPhone,MacOSX,Objective-C,Programming,Tips | , , ,
― Vincent Gable on May 19, 2010

How to remember Cocoa memory management:

Think NARC: “New Alloc Retain Copy”. If you are not doing any of those things, you don’t need to release.

–Andiih on Stack Overflow

Personally, I like to immediately autorelease anything I NARC-ed, on the same line. For example:

Foo* pityTheFoo = [[[Foo alloc] init] autorelease];

Admittedly, this makes for some ugly, bracey, lines. But I think it’s worth it, because you never having to worry about calling release if you also…

Use a @property (or Setter) Instead of retain

In other words I would write an init method that looked like:

- (id) init
	self = [super init];
	if (self) {
		_ivar = [[Foo alloc] init];
	return self;


- (id) init
	self = [super init];
	if (self) {
		self._ivar = [[[Foo alloc] init] autorelease];
	return self;

(Or [self setIvar:[[[Foo alloc] init] autorelease]]; if you are one of those folks who hate the dot-syntax.)

It’s debatable if using acessors in init and dealloc is a good idea. I even left a comment on that post arguing against it. But since then I’ve done a lot of reflection, and in my experience using a @property instead of an explicit release/= nil solves more problems then it causes. So I think it’s the best practice.

Even if you disagree with me on that point, if the only places you explicitly NARC objects are init, dealloc, and setX: methods then I think you’re doing the right thing.


The last piece of the memory-management puzzle are retain cycles. By far the best advice I’ve seen on them is Mike Ash’s article. Read it.


  1. “Personally, I like to immediately autorelease anything I NARC-ed, on the same line.”

    Man, I thought I was the only one…

    Comment by Joel Bernstein — May 19, 2010 @ 11:30 pm

  2. Hi, just asked a question on SO about this. It will eitherGet no notice at allStart a huge debate(most probably) get a few tepid answers and no real conclusions :)

    Comment by Daniel Rosenstark (yar) — May 26, 2010 @ 4:37 am

  3. +1 for immediate autorelease. In fact, if you’re using the empty constructor, then I’m pretty sure you can use `new` instead of `alloc, init, autorelease`.

    Foo* pityTheFoo = [Foo new];

    Comment by Josh — October 4, 2011 @ 9:58 am

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