Clarification of Autorelease Usage

Question

In most of the code that I've sen using autorelease, the object is ultimately returned from the function.Clearly release cannot be called after this point and autorelease is the way to go. However in situations where the object is going to passed to another object that will retain it is using autorelease just as valid?

For example

-(void)foo
{
   SomeClass *someObject = [[[SomeClass alloc] init] autorelease];
   //Do some things
   self.someOtherClass.someProperty = someObject;
}

Is there any practical difference to releasing the object after it is assigned to someProperty:

-(void)foo
{
   SomeClass *someObject = [[SomeClass alloc] init]];
   //Do some things
   self.someOtherClass.someProperty = someObject;
   [someObject release];
}

Are there any situations where the later is more preferable to the former?

score 1 · Accepted Answer · edited May 23 '17 at 12:12

1

Both are acceptable, but you are accouraged to use the release version to avoid memory spikes an other problems.

It's acceptable to release here because you can assume that the receiver of the object will retain it, if it needs if later. So you can safely release as soon as it's given.

edited May 23 '17 at 12:12

Community

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1

answered Oct 20 '11 at 15:45

gcamp

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Only an issue if you're doing a lot of heavy lifting. You can usually get away with `-autorelease` for smaller objects like `NSString` or `NSNumber`. It's a judgement call. – Jonathan Grynspan Oct 20 '11 at 15:47
@JonathanGrynspan agreed, it's a guidance, not a rule. – gcamp Oct 20 '11 at 15:48

score 0 · Answer 2 · answered Oct 20 '11 at 16:50

I think the latter will always perform slightly better in terms of memory usage and CPU usage, but only by a tiny amount per allocation.

Feel free to use the former if you prefer not to write three lines of code and are not having a performance problem. Note that the former can actually be written in one statement without a local variable at all.

Clarification of Autorelease Usage

2 Answers2